Etiquette
1. Observe frequency control. Some people get upset when they crash, and it's always re-assuring to know your transmitter was in the impound, and you had control of your channel.
2. When someone crashes, walk with them out to the wreckage. They probably won't ask for help, but they will always appreciate it. Don't say anything except mumblings of sympathy. When you find the plane, the pilot will be slightly in shock, so you keep your wits and find all the parts. I would avoid saying things like "This can be rebuilt". Stick with, "Can I help you carry this stuff?"
3. As far as talking to flyers, a lot of the very experienced pilots can talk and fly at the same time, and are happy to, but flying does take a lot of concentration, so I'd mostly leave them alone while their plane is in the air. I once had this guy come up to me and start talking and wouldn't go away no matter what I did. I finally had to bring my plane in it got so distracting!
4. Be really nice to spectators, newbies, small children, but make sure they stay where they are safe.
5. Please, do not offer help unless the person asks, or has very obvious body language. I had this guy come up totally unasked and tweaked my needle valve before I could stop him ("You sound lean," he said). I then informed him that I had just noticed that I forgot to connect the tube to the muffler, and would he please put the needle valve back where it was!
6. Let folks know you are new. I once visited a club, and I was welcomed to fly, but I should have asked more about local rules. They had very strange (to me) rules about where you could set up, and it was very awkward when folks very nicely tried to explain to me that I was breaking some rule I couldn't figure out. I would have been much better if I had simply asked ahead of time about the rules. For example, some clubs are *much* more concerned that you fly "the pattern" (everybody takes off and lands the same direction, plus flies pretty much in an oval the same direction) than other clubs where you pretty much just try to avoid mid-airs.
7. Last one: This hobby tends to attract introverts, the guys that love to putter around their workshop alone for hours. As introverts, they tend to be reserved, and are quite happy being alone, and if they are tired, they need to be alone. So don't take it personally if someone seems to want to be alone. Work it slowly. Maybe after 1/2 hour, a guy might ask a question about your plane. Once they realize you're not going to make any sudden moves, these guys can be incredibly friendly and helpful, but they can also appear cliquish. If you're expecting typical extrovert behaviour ("Hi, welcome to our club, I'm Mike, and I'll be your tour guide!"), you're likely to mistake reserve for unfriendliness.
--Mike