To give you more to read:
1. Watch that youtuber play mission 1 and where to get special encounters. Make sure you have someone with 100% outdoorsman ASAP (e.g. Farsight) to reject all the random encounters.
2. Play mostly in Real Time mode. With Turn Based modes, you waste more Perks on Turn-based specific things, and you waste too many APs every turn when you end up with odd AP just not enough to do anything productive. No such problems in Real Time. Moving in RT mode don't even deduct AP, so if you move faster then target when kiting, you can run/stop to accumulate APs until its enough for another shot. (See? Things like this are not explained anywhere.)
3. Loot as much as you possibly can, and store everything in lockers and vehicles (just open inventory when inside) instead of selling to the quartermaster. Quartermaster is a loss-twice scenario: Sell at rubbish price, and buy them back at blackmail price when you need some of it back, so don't. Only trade with him for really rare/good items, using the person with heavy skill and Perk investments into Barter.
4. Go to wiki's recruits page to plan your team members and perks up to Lv21 (up to 7 usable perks). Low level members are best because they're blank canvases. Keep people who has SPECIAL of at least x74x676 (mutate to Gifted as required) for these bread-and-butter (and best) perks: {Tag!, Mutate!, Lifegiver x2 as soon as Lv12, Bonus Ranged Damage x2, Bonus Rate of Fire, Sharpshooter, Hit the Deck}. Get More Criticals x3 instead of Bonus Ranged Damage x2 for your Sniper. Also try to mutate him/her to Jinxed for a secret 20% boost to crit chance. *Snipers are for disabling at long range, not for damage in this game. Disabling needs as many crits as possible (even 0 damage is ok), so Sniper Rifle is better than Laser Rifle for this purpose. (1 less AP cost)*
5. Some skills are useless, some you'll get enough from skill books(if you put effort to get them all), avoid melee skills, which leaves below skills that are worth actual skillpoints:
- Ranged weapons skills (all members 180~200% each specialized in 1 or 2 different weapons classes: small guns for early game but still good to keep 1 sniper with 200% for aimed-shot to disable things at end game, big guns are good from midgame to end, Energy for end game)
- Lockpick (1 member, need 120% + holding 2 of the best lockpicks by end game)
- Sneak (need 180%+ for most team members when they get Powered armour)
- Traps (1 member, need 130%+ quite early, books won't be enough)
- doctor (1 member, just need around 100% + holding 2 doctor's bags)
- (Optional) Steal (1 dedicated member, need 130%+ and "pickpocket" perk, and optionally high charisma + "Bluff Master" Perk for less save-scumming. e.g. Sharon+Mutate+Divine Favour)
- Bartering (1 dedicated member, e.g. Stitch due to good nature and high skill per level. Need around 200% and trade-related perks)