Be aggressive for the first 5-8 minutes of a game so you can gather heals/weapons/ammo/nades/armor much more quickly.
Camping, yea i hate this shit too, i fought against the meta for a long time and managed to get pred by being aggressive but you can and will be punished for fighting people. Play wraith, pathfinder/caustic and wattson and camp buildings and hiding spots until your Top 3 and then wait for a gun fight and 3rd party.
Fighting mid-late game is really bad. If you cant roll a team in about 30 seconds, leave and run away, a 3rd party is going to happen no matter what. Wraith portals really help here because they disappear after 60 seconds.
Weapon Meta, R99 and any sniper is pretty much meta, if you don't like snipers and prefer a wingman that's also fine but rn you should use an R99 and any sniper that pleases you.