The Task Force Ripper team I've been with for the last year or so hasn't had any discipline problems. We know that when we're told to do something, there's a reason for it. All of the team leadership (besides myself) are former military, most of which with actual combat experience, so I know they know what they're talking about.
Muzzle discipline and other safety-related things are always reinforced at the start of every game, and for new players, this means they learn to play airsoft from a safety-first perspective. We have "clear-weapon" rules at staging areas, goggles-on once "in the box" and everything else, but the important part is that the new players get the safety part learned early on and reinforced.
Discipline is a reflection of respect for leadership and the rest of the team, and a team with good personality cohesion will have respect for each other, and thusly, the leadership. Part of getting that personality cohesion in place is spending some extra time with the team, like at dinner, a party, or something like that. This is also a good idea for teams to get together with other teams. Talk to Raptor5191 about discipline in his team, his TEF guys are pretty squared away, responsive to orders, but never running around acting too uptight. The thing to remember is that people pay good money to play airsoft, and you gotta respect that. You're not paying them to be there, so treat them with respect and they'll do the same for you.
You know, do unto others.
Unless they're the opposition and the game's started, then do unto others before they do unto you.