1. Holsters: Generally speaking, most of us use a strong-side OWB holster when OCing. With that in mind, I personally prefer to use a holster which is neither 'flashy' nor crude/cheap-looking. A retention system of some kind is a plus (thumb-break, SERPA, CARRY-LOK, etc...). Paddle or Pancake holsters are most comfortable, for me.
2. Clothing: I try to not look like either a ragamuffin or a police-officer when I carry. Again, nothing 'flashy' nor crude/cheap-looking (ie: shirts with violent/cruel or gang-related material). I try to stick with plain shirts (sometimes with patriotic or pro-2Agraphics),and jeans or pants which are in good condition (and fit properly).
3. Manners: Very important! Look people in the eye, smile (optional), and be non-confrontational. Keep the hands off of the gun, and out of the pockets as much as possible.
4. Citizen Encounters: With the above manners in mind, just be polite and respond in a positive and reasoning (not condescending) manner.
"The police can't be everywhere, so I take the responsibility of protecting myself very seriously."
"It's no different than having a fire-extinguisher to protect ones-self from fires, or an air-bag to protect you in an accident... You never know what will come at you that might harm you, and it's best to be prepared."
"As long as there are criminals in this world, there will always be victims... I refuse to be either"
5. LEO Encounters: Similar to above... Andbesides, they should know better than anyone what criminals are capable of, and the force occasionally required to stop them. If I am within the law, I am fine... If the LEO knows the law, and is merely curious or conversational, GREAT! If the LEO does not know the law, I would try to politely educate them.