...I would hope everyone knows not to put your hand on the gun.
And yet we had an officer recount an experience on this thread where a person, during a traffic stop, took a gun out of the glove box without thinking about it.
I think it's good for people to think about this kind of stuff ahead of time. It's not complicated, but some of it is pretty important.
I recommend people NOT carry their gun in the same location where they have their registration/insurance to avoid having to mess with the gun or reach towards it during a traffic stop. You don't want the gun to even make a visible appearance unless the officer decides it is relevant.
I recommend NOT saying things like: "I have a gun." or "My gun is on me." or anything along those lines. If you have to inform, the best way is to provide your carry permit with your license. If you don't have one and need to inform, then say something like: "I have my CCW with me." or "I'm carrying.", something that sounds routine and gets the point across without saying the word 'gun'. Watch some shooting videos and see what happens in a situation where an officer starts saying: "Gun." or "He has a gun." There are negative associations that are nice to avoid.
I recommend people not try to get everything ready for the cop before he approaches. Because he will see you getting something ready for him without knowing for sure whether it's an ambush or just your license and registration.
I recommend not creating needless strife during the stop, not because a cop is going to shoot you if you argue with him, but because it's pointless and escalates a situation that involves at least one armed person, probably, on this forum, two. In a disaster, it virtually always takes more than one contributing circumstance to cause a real catastrophe, the more circumstances you control, the less chance of things getting out of hand.
I recommend always being polite because, for one thing, you should really always be polite. The vast majority of cops are doing their job and are decent folks and don't deserve anything other than being treated politely. The very few that are a problem should be treated politely so you don't get them spun up.
I recommend people make themselves as visible as possible to the cop so they can easily see that you are sitting there doing nothing and waiting for instructions. Roll down windows if the tint is dark and you have power windows (if you have manual windows, wait for the officer to approach). Turn on the domelight if it's dark outside.
I recommend that people turn the engine off, or at least put the car in park so the officer doesn't have to worry if you're going to hit the gas and take off.
I recommend pulling over in a spot that doesn't endanger you or the officer during the stop and that makes things go as smoothly as possible. If you there's no good place to stop immediately, then slow down a bit and put on your turn signal to let him know you're looking for a place to stop rather than just driving on at speed and leaving him wondering what's going on.
I recommend not getting out of the car unless ordered to, both for your safety and to let the officer handle the traffic stop at his own pace.
I recommend telling the officer what you're doing before you do it--even if you are following instructions.
There's a video of a person getting shot for abruptly reaching into his car for his license after being told to get his license by the officer. The officer didn't realize that the guy didn't have his license on him and assumed (incorrectly) that the guy was going for a weapon when he abruptly turned and leaned into his car. The officer was absolutely dead wrong to shoot him, and it wasn't really the guy's fault that he got shot, but the fact remains that if he had told the officer that his license was in the car and asked if he could get it before just abruptly reaching into the car, the odds are extremely good that he would have remained UNshot. An outcome that both the officer and the man really wished for after the fact since the guy was badly injured and the officer was fired, charged, convicted and sent to prison for 5 years.