Level 8 and Still Lost

I bought this game a few days ago when it went on sale, only started playing yesterday, I think, and have got myself to level 8 mainly by joining missions and just following whoever looked like they knew what they were doing, which is fine, but I just don’t feel like I’m really contributing much other than killing the odd enemy here and there. All the objectives are pretty much done by the time I get close so I don’t really think I’ve learned much about the mechanics of the objectives.

It seems like a very simple game at first glance, but there’s more to it than my casual eye initially gave it credit for…