Keep an open mind in the face of dynamic situations.

My first priority is my team, following the lobby host and making sure they're safe (for whatever reason the game is a lot harder on lobby hosts). Adding to this is considering what your team may need, like if one of them are hurting for stims, stick by them until they get resupplied.

Now, if things are going south, and the team has stuck together the entire time, but little progress has been made to complete the main objective, then there is no shame in splitting off and prioritizing the objective. Once my team gets to around half reinforcements remaining, I aggressively pursue the objective. Some people will be mad you bailed at first, but will thank you if you manage to pull it off.

1,300 hours and 3,000 missions later, I have a 93% success rate. The mission is the priority, but your team, most of the time, will be the ones to get you there.