After losing and winning and really enjoying the game, here are a few hard-won tips that might help you.
There are times when XCOM 2 feels more like a board game and less like a computer game. I think that is probably how they designed the strategic part of the game and it works. But unlike a traditional board game, they don’t disclose the rules or the trade-offs at the start. This means you don’t really appreciate how your early-game choices impact the late game until your second or third play-through. This is ultimately why it is beneficial to play through in Easy mode first. Frankly, they should have called that “Normal” and called Veteran mode “Advanced” or something because it feels to me like there are advanced rules being used in Veteran that Easy doesn’t have. For example, almost all missions in Veteran have a time limit, while on Easy mode many don’t.
Resistance Communications – must have building ASAP and it must be expanded. Don’t do anything else until this is built. Why? Because without it you can’t assault the Advent facilities in those far-flung regions and those missions are the best way to slow down the advance of the Avatar project. It is the same as expanding your satellite network in the prior game.
Expand the resistance network when you can – there are benefits (ala Risk) to owning an entire continent that make it worth your time to complete an area and you need to be able to assault whatever facilities or crashed UFOs show up in those regions.
After Comms, I think the Guerrilla Tactics School build should be next on your list. It lets you have a 5th or 6th trooper on missions. I recommend building this before the required Proving Grounds so that means you also need to get a power boost somewhere early (hopefully you’ll get one off the strategic map).
When the game alerts you to a Red mission (Retaliation, UFO down, etc.) you MUST take and complete that mission or suffer a serious setback – you lose that region of resistance contact AND any region it is connected with. That can lose the game for you because the time and Intel costs required to re-establish contact is killer.
The guerrilla missions are also pretty much required because the benefits of winning are usually big (like setting back the Advent calendar or Retaliation event by 2 weeks.) Don’t worry about the mission difficulty either – pick the one with the best benefit.
Upgraded weapons are nice, but upgraded armor seems even better. Weapons are overall pretty powerful at the start and more defense benefits you early more than increased weapon damage. If you can, use the Black Market to increase the research rate of the armor project. But watch out at that Black Market – those Intel points are required to expand your resistance network and they aren’t always easy to find. And like in previous games, you really only want to sell items you know you don’t need. If you aren’t sure, hold onto them.