It's all about the size of your stick Edit
You run this irradiated, radroach infested town! Edit
To assert your authority, it is advised that you always carry your gun openly and keep it loaded. Your objective is to have just enough force on show that nobody is going to start any trouble, whilst not being percieved as a threat to the general safety of the community. The same goes for any clothing you have: wear your strongest armour, but remove any headgear that covers your face as you approach a town so that they don't take you for a raiding party.
Can I have two tickets to the gun show, please? Edit
At some point you will find yourself in the presence of an organisation or town that has bigger, meaner guns than you. Your actions at that point will decide whether you earn their respect, or you earn a chest full of 5mms and a long stay in a shallow grave. It would be wise to do exactly what they ask, or avoid them all together. Chances are you will have heard of them if they are very well armed, so if they are renowned merciless psychopaths then you would do well to keep on walking. If at any point they ask you to remove your weapons, you must decide whether this is simply protocol, or they are about to kill you. In most situations where the latter is the case you would not have even reached their gates; however, you must stay alert and be ready for anything. If it feels safe, give up your weapons, but keep a small knife or pistol concealed somewhere on your person in case your host changes their mind.
Don't start nothin'. Won't be nothin'.Edit
Overall, it's all about staying out of trouble. It doesn't matter if some psycho junkie insults your mother, popping two in their chest will always end badly. Being well armed will stop most people from starting with you, then all you have to do is not start with them. Easy, huh?