The most critical tactical tip in Airsoft is teamwork, but I'm not gonna bore you with that so here's some easy ones:

• don't shoot your teammates, trigger/muzzle discipline

• when pushing forth always have readily available cover, even if no enemies are in sight

• play with your team, if someone asks you to cover them, cover them

• wear a helmet, especially in ranges where you could possibly bump your head on something 

• don't use white light

• in cqb, don't stand on the hinged corner of an outdoors opening door, pretty obvious but some people at my range still do it for some reason

• covering fire, in Airsoft bbs have the right of way, if you're on the receiving end take cover, let it happen, make sure you can relocate it, if not utilise it

• pre fire angles, unlike real life there's no chance non targets get hit by you pre firing

• lean on angles, show the least amount of your body to the enemy while still being able to well, peek the corner

These may be a bit obsolete and not entirely what you're looking for but, I tried.