I'm just jumping in here, but in my case trying to go through the campaign on the easiest skill level just so I can understand the mechanics better... I'm not really sure what I'm doing. People say you should have this or that by such and such month, yet there's so much research to do and a fair bit of randomization in what missions you'll get and what's in them (which then determines future research options) that it becomes a bit of a mess.
Unlike the classic X-COM campaign, there's no clear indication as to how I'm progressing in the campaign. I know the fun is in the journey (and it's quite a journey), but after quite a bit of hours of play I end up spinning my wheels almost, running out of research (apart from eternally Socializing), wondering how to make tangible progress towards an end state.
Sometimes I'd cheat, adjust the funds in the savegames or mod the Ubers to be unfairly powerful, just so I could progress. But then I'd get my first alien base mission equivalent and I'm like, WTF my guns are doing NOTHING to certain enemies because I have zero understanding of how to take down shields despite all my shameful cheating. I feel like I'm blundering through the game blind without knowing whether I'm playing it "right" or putting myself in a situation where I'll never properly progress. But my understanding is that this is intentional - it should be a learning experience. But on the wikis and posts I mostly just read gameplay tips on how to handle situations (which is useful), but not much about how to actually progress towards an end state.
I can't do a Meridian and spend nearly a year on a single playthrough. And that was an earlier version of the game, with less stuff!