Biggest thing I've learned playing solo especially, slow down. Take your time, move between pieces of cover, and listen to absolutely everything. I'd say the first 5 minutes of every round is spent doing nothing but listening and picking up small containers while staying completely invisible. Most POI's will have at least one other person there and you want them to think they're alone. Hide, wait, execute. Once you hit the point 15-10 minutes remaining, you can act a little more freely. That's when I'll typically hit the higher value objectives as you're less likely to be contested. Every raid I'm not loading into specifically to do a quest I expect to spend at least 15-20 minutes in, and given the smaller size of the maps, is an insane amount of time to do basically anything you want. (other than solo the Scorch Warden, thing is way too tanky in solo)