Ya know, it's a matter of common sense. Number one if your gonna carry then figure on carrying every day and absolutely don't carry without a permit! I did for years and looking back, that was one of the dumbest things I ever did. Number two decide what you situations will be. Let the potential threat level and expected situational wardrobe guide you. There are times I can get away with a .38 derringer: white shirt and tie (no not the best of options but most likely with where I am, I want need anything), if I can dress casual with untucked shirt the snub .357 IWB, if you are wearing a coat then you can certianly conceal something larger. There are times when going into an area when potential for danger is higher then carry bigger and dress to cover. Try to stay out of them places, it's better to be a live chicken than dead duck or a jail bird. No hard fast rule just think and plan ahead. Most of all it's what works for you. Remember you are carrying a weapon with the power of death, an awesome responsibility, one which must be considered with the attitude befitting it.