Of the tactical servers I have been on, they had the following common rules:
No running or jumping. Everbody is supposed to stay in crouch mode the whole time. The only time you are allowed to run is if you are under fire. The problem is that once you come under fire, you’re pretty much dead. The jumping rule is to prevent bunny hopping, which is when you jump up and down while being fired upon, but I’ve personally witnessed several people do this, then later claim they hit a wrong key.
No blind nades. I got into an argument one night over this one. I killed one of the regulars with a nade, and he promptly reminded me of this rule. Throwing a blind nade is when you just toss a grenade into a building or over a wall and hope to catch somebody with it – you’re blindly throwing it. In my case, I saw a guy step out and shoot, then hide in a stairwell, so I threw the grenade in the stairwell and he accused me of blind nading. I explained that I just saw him there and we went back and forth before I gave up. The problem is that I’ve seen the same argument happen numerous times with other players.
Sights must be up when firing. In other words, no shooting from the hip. Sometimes when you come around a corner, the split second it takes for you to put your sights up is all it takes for the enemy to gun you down. Walking around with them up also blocks a lot of your field of view. If the server has a Kill Cam turned on, the person you shot will often tattle if you fired from the hip.