Most of my pet peeves are centered on common courtesy. First, it drives me nuts when the range is hot and someone new comes up and asks if everybody will go cold so they can go put up a target. Everybody stops shooting and safes their rifles/pistols, and then, instead of running on down a setting up a target real quick, the jackass then heads back out to the parking lot and spends the next 5-10 minutes unloading their crap from their car to the line, looking for their staple gun, digging in the trunk/bag for staples, etc. Being courteous is that not hard. Don't ask everybody on the line to go cold if you are not absolutely 100% ready to go put up your target. If the range is hot when you arrive, then just go ahead and move all your gear to the line and get all your targets and stuff ready to go FIRST, then ask the other folks to go cold. And conversely, if the range is already cold when you show up, drop whatever you are doing and go set a target RIGHT THEN. You can always move your stuff to the line after it goes back hot.
Second, I am a firm believer in the application of interstate rest stop urinal etiquette to firing ranges (especially indoor, but it should apply to all). I hate it when I am off to one side of the range, and there are plenty of open lanes, but somebody comes in and sets up right next to me. Especially if they have an AR or something with an obnoxious brake. Whenever I am shooting my braked stuff, I try to give folks as much room as I can.
Third, I hate people that bitch about the safety/range rules without first pulling out their checkbook and offering to pay all future liability insurance premiums and agreeing to be financially liable for all injury or damage to the equipment, property or persons that occurs afterwards if the rules are changed to suit them. I went to a range once, and after they finished giving me what I deemed to be draconian rules, I thanked them politely and left to find a range that better suited my needs. I may not think their rules are appropriate for my perceived level of firearms self-expertise, but at the end of the day, it is their property, their liability and their right to mitigate that to THEIR satisfaction, not mine.