We call it a culture of safety at work. this means that in all of our actions with the guns, we consider what can happen if it was to fire--both in and out of games.
I think that 3 levels of safety can be built:
1. Safe zone, located to physically separate players from flying BBs. mags are never in, safetys always on and caps, sock etc always on. Goggles are not mandatory. I don't think this zone should be the re-spawn
2. shooting gallery, located next to the safe zone. Goggles always on, mags in and shooting allowed, but controlled an in a safe direction (away from the palying area). NO human tagets.
3. playing zone-play area. Goggles always on. within this area safteys still used when going to and fro, and barrel covers on when exiting area. Players with barrel covers of a sort are not viable targets.
The tough part is making a safe zone that is actually safe during a game.