Get all of the guns you want to use.
Remember to get multiple.
After you get the guns use Infinite Yield (below) to fly out of the map.
Once out of sight of other players use inf Yield to go into freecam.
Once in freecam turn the speed up tp 100 to get back to the map once in the map change speed to 1 or 2.
Now you can troll people and shoot people and they wont be able to see you.