...I think I brought over some gaming mentality too. If it's just a walk on game, think of it like a huge PvP game of randoms (like... World of Tanks).
Take the 30 seconds to a minute at the beginning of the round to find quick cover and watch everyone else. Where they move, where lanes show up. Establish the field and where people are before making your move and you can help your team/co ordinate as necessary.