Ettiquite- what's the best way to contact your in-world friends?

depends on the person. Some people don't mind if you show up. if you don't drop by occasionally they think you're ignoring them. Some people prefer an im first. Personally I don't mind either, but have a purpose. I'm not big on "I'm just saying hi". The impolite way is "Join me in [sim name here]!" TPs are not acceptable forms of greating.