Leniency
This is the thing I cannot stress enough. The primary point of jail is for us all to have fun, and its not very fun if you get killed for facing cells when you were ordered to face away. There's times when half the T team is killed straight out of cells for not fully understanding these orders, and it's painful to even watch it happen. The following will cover basic non threatening situations.
A lot of guards will kill a prisoner for very minor things. Prime examples are killing a T straight out of cells for twitching, or exiting a second or 2 late. This person now has to wait an extreme amount of time before he can enjoy the game. Not everything needs to be so black and white. You don't need to kill him the first time he twitched, but neither should you need to remind him 5 times in 30 seconds that he is going the wrong way. If a T deviates from the path, point him in the right direction. As long as he doesn't do it for the sole purpose to obtain a gun or something, then his unintentional detour did nothing to put your team in danger, and there isn't much of a reason to kill him for it.
I myself will "usually" only kill a prisoner for something that I deem dangerous to me or my team. Things like detouring over to a CT or a gun are generally things I would kill for. Detouring towards me, I usually just back up and let the T know he is making a mistake and should follow the orders, killing him if he continues his pointless chase.