Here's a quick run-through.
Before everything begins, you are given four groups to ally yourself with, namely GA (Heavyweights) , Rosenthal (Balanced Middleweights), BFF (Snipers) and "Independent Group", which is not allied to anyone. Your Shop will depend on which group you chose at the start. If you choose Independent Group, you start off with a pure AALIYAH model, with 1 HITMAN machine-gun, 1 03-DRAGONSLAYER energy blade and 1 TRESOR plasma cannon (the one with 10 ammo only). You get NO shop, as you salvage parts from the enemies that you destroy in battle (The shop is provided by the League of Rule Companies. Since you're not allied with them, no shop for you). This is by far the hardest route, since the Order Matches (a.k.a. Arena matches) aren't counted since they are also part of the Collared Rank (and apparently they don't want you blowing up your allies). You get parts from defeating an enemy NEXT in missions, getting all their parts at once when the mission ends. Among these groups, Rosenthal's the easiest choice since not only do they have the most balanced parts, but the Rosenthal starter AC, Lancel, can immediately use Assault Armor (hold both change weapon buttons and press the overboost button), helping you a LOT in both missions and the earlier Order Matches. GA's heavyweights and BFF's snipers have an obvious fighting style, so I won't delve into those anymore.
If you chose any of the first 3, you're a member of the Collared Rank, a group that will work for anyone that pays the right price, exactly the same as the Raven's Nest and Raven's Ark of the older games. The different factions in there are the "League of Rule Companies", made up of smaller companies, such as Algebra (formerly Eqbal in AC4), Global Armaments (GA), Omer Science, Rosenthal, etc. and ORCA, a group that seems to be the guardians of the "CRADLE"s, gigantic aerial Kojima-powered colonies housing 20 million people each. The League of Rule Companies is made up of the old AC4 companies (or their remnants) and monopolizes the world's economy and spreads it out throughout its smaller companies. It is to be noted however, that this faction still wants Earth to survive, considering that its level of Kojima pollution has been increasing steadily (and of course, they are based on Earth, so yeah). Within this faction, companies have made their own alliance, which is the reason why companies within the League still fight against each other. There is one independent company called Line Ark. Although Line Ark is "neutral" to the League, it does not align its principles to the League's, so if the League tries to oppress them, they will fight back.
Regardless of which group you chose, at the start of the game, you're just given regular non-storyline missions, such as demonstrating the power of a NEXT (the first stage), a recon mission to investigate the illegal construction of an Arms Fort and to destroy it and everything else if confirmed, and much more, all made by the different company alliances. The first "true" storyline mission is when the League hires you to go up against Line Ark and their ace, codenamed "White Glint". I won't spoil the storyline, so I'll stop here.
During your first play-through, you'll only be allied to the League. Once you finish it, however, new missions are unlocked as you proceed through the chapters, leading to a new ending. The old ending may be repeated however, so choose your missions wisely.
When you finish chapters and finish Hard Mode missions, you receive FRS, which you can use to Tune your NEXT. The categories haven't really changed from AC4s, but the order of some categories have been changed.
"CAPACITY" has 4 sub-categories, such as weight limit (you can tell by checking the part name, which happens to be the Leg part), EN Capacity (recovery rate), EN Output (supply) and Kojima Particle Supply (important for Primal Armor, overboosting and Assault Armor). A note here is that the Weight Limit was the last sub-category in AC4, but is now the first in AC:FA, so check your part names to be sure which is which. Oh yeah, I may have mixed up the Output and Capacity sub-categories, so just experiment until then. Here's a tip: the smaller value is your recovery rate, the higher values is your energy supply. I'll edit this post when I check them out again.
"ATTACK" determines Arm maneuverability, firing stability, precision rate (only good for snipers, so non-snipers don't have to worry about this) and EN ability (ever since AC4, Arms have always had their own compatibility to Energy weapons. The weaker this is, the weaker your energy weapon damage will be. Although it says EN ability and has the Arm part name displayed, surprisingly, this also affects Back weapons).
"CAPTURE" improves FCS performance, such as Lock-On speed, etc. I can't say much about this since I have never tried it before, even in AC4.
"PRIMAL ARMOR" determines PA effectiveness, such as PA Rectification (PA Defense) and a few others. Once again, I never bothered to try this since AC4, so I can't say much regarding this category.
"BOOST" determines the normal boost speed of all your boosters, namely Forward, Back, Vertical and Side Boost speed. Vertical Boost still utilizes your main booster, but it affects your main booster's aerial boost speed and ability.
"SPECIAL BOOST" determines forward, back and side Quick Boost and Over Boost speed. Should be pretty obvious.
"STABILITY" determines how much recoil your parts (head, arms, body and leg) receive from firing or receiving fire. This has a somewhat detrimental effect on your NEXT, but it might be worth it if you tend to encounter high-recoil weapons on the field. Note that your NEXT's balance also affects your stability, so check your balance in the "Stabilizer" menu, right below "Tune".
"CONTROL" improves the movement and control of your NEXT. Braking Ability, Landing Ability, Turning Ability and [something else that I forgot] are located here. Turning Ability is definitely something to be considered, as its really helps control your turning arc when boosting.
I'll stop here for now. Remember, when you're getting beaten on a mission over and over again, you can go online co-op and ask for assistance there. You and your ally will split the reward 50-50. I would suggest connecting to the Japan channel, since they have the most number of veterans and experts out there.
Before everything begins, you are given four groups to ally yourself with, namely GA (Heavyweights) , Rosenthal (Balanced Middleweights), BFF (Snipers) and "Independent Group", which is not allied to anyone. Your Shop will depend on which group you chose at the start. If you choose Independent Group, you start off with a pure AALIYAH model, with 1 HITMAN machine-gun, 1 03-DRAGONSLAYER energy blade and 1 TRESOR plasma cannon (the one with 10 ammo only). You get NO shop, as you salvage parts from the enemies that you destroy in battle (The shop is provided by the League of Rule Companies. Since you're not allied with them, no shop for you). This is by far the hardest route, since the Order Matches (a.k.a. Arena matches) aren't counted since they are also part of the Collared Rank (and apparently they don't want you blowing up your allies). You get parts from defeating an enemy NEXT in missions, getting all their parts at once when the mission ends. Among these groups, Rosenthal's the easiest choice since not only do they have the most balanced parts, but the Rosenthal starter AC, Lancel, can immediately use Assault Armor (hold both change weapon buttons and press the overboost button), helping you a LOT in both missions and the earlier Order Matches. GA's heavyweights and BFF's snipers have an obvious fighting style, so I won't delve into those anymore.
If you chose any of the first 3, you're a member of the Collared Rank, a group that will work for anyone that pays the right price, exactly the same as the Raven's Nest and Raven's Ark of the older games. The different factions in there are the "League of Rule Companies", made up of smaller companies, such as Algebra (formerly Eqbal in AC4), Global Armaments (GA), Omer Science, Rosenthal, etc. and ORCA, a group that seems to be the guardians of the "CRADLE"s, gigantic aerial Kojima-powered colonies housing 20 million people each. The League of Rule Companies is made up of the old AC4 companies (or their remnants) and monopolizes the world's economy and spreads it out throughout its smaller companies. It is to be noted however, that this faction still wants Earth to survive, considering that its level of Kojima pollution has been increasing steadily (and of course, they are based on Earth, so yeah). Within this faction, companies have made their own alliance, which is the reason why companies within the League still fight against each other. There is one independent company called Line Ark. Although Line Ark is "neutral" to the League, it does not align its principles to the League's, so if the League tries to oppress them, they will fight back.
Regardless of which group you chose, at the start of the game, you're just given regular non-storyline missions, such as demonstrating the power of a NEXT (the first stage), a recon mission to investigate the illegal construction of an Arms Fort and to destroy it and everything else if confirmed, and much more, all made by the different company alliances. The first "true" storyline mission is when the League hires you to go up against Line Ark and their ace, codenamed "White Glint". I won't spoil the storyline, so I'll stop here.
During your first play-through, you'll only be allied to the League. Once you finish it, however, new missions are unlocked as you proceed through the chapters, leading to a new ending. The old ending may be repeated however, so choose your missions wisely.
When you finish chapters and finish Hard Mode missions, you receive FRS, which you can use to Tune your NEXT. The categories haven't really changed from AC4s, but the order of some categories have been changed.
"CAPACITY" has 4 sub-categories, such as weight limit (you can tell by checking the part name, which happens to be the Leg part), EN Capacity (recovery rate), EN Output (supply) and Kojima Particle Supply (important for Primal Armor, overboosting and Assault Armor). A note here is that the Weight Limit was the last sub-category in AC4, but is now the first in AC:FA, so check your part names to be sure which is which. Oh yeah, I may have mixed up the Output and Capacity sub-categories, so just experiment until then. Here's a tip: the smaller value is your recovery rate, the higher values is your energy supply. I'll edit this post when I check them out again.
"ATTACK" determines Arm maneuverability, firing stability, precision rate (only good for snipers, so non-snipers don't have to worry about this) and EN ability (ever since AC4, Arms have always had their own compatibility to Energy weapons. The weaker this is, the weaker your energy weapon damage will be. Although it says EN ability and has the Arm part name displayed, surprisingly, this also affects Back weapons).
"CAPTURE" improves FCS performance, such as Lock-On speed, etc. I can't say much about this since I have never tried it before, even in AC4.
"PRIMAL ARMOR" determines PA effectiveness, such as PA Rectification (PA Defense) and a few others. Once again, I never bothered to try this since AC4, so I can't say much regarding this category.
"BOOST" determines the normal boost speed of all your boosters, namely Forward, Back, Vertical and Side Boost speed. Vertical Boost still utilizes your main booster, but it affects your main booster's aerial boost speed and ability.
"SPECIAL BOOST" determines forward, back and side Quick Boost and Over Boost speed. Should be pretty obvious.
"STABILITY" determines how much recoil your parts (head, arms, body and leg) receive from firing or receiving fire. This has a somewhat detrimental effect on your NEXT, but it might be worth it if you tend to encounter high-recoil weapons on the field. Note that your NEXT's balance also affects your stability, so check your balance in the "Stabilizer" menu, right below "Tune".
"CONTROL" improves the movement and control of your NEXT. Braking Ability, Landing Ability, Turning Ability and [something else that I forgot] are located here. Turning Ability is definitely something to be considered, as its really helps control your turning arc when boosting.
I'll stop here for now. Remember, when you're getting beaten on a mission over and over again, you can go online co-op and ask for assistance there. You and your ally will split the reward 50-50. I would suggest connecting to the Japan channel, since they have the most number of veterans and experts out there.
[All systems online. Kojima output normal. Synchronizing AMS Compatibility... Done. Engaging Primal Armor... Done. All systems green. Firing main boosters.]
"Blackwing, let's fly!!"
"Blackwing, let's fly!!"
