Just speaking for myself, I've found gun shop people, fellow owners, range participants, IPSC and IDPA members, and club members to all be a very congenial and helpful group. In all the years I've been shooting and participating in this culture, I have had no bad experiences whatsoever.
Some rules of thumb I follow are: be polite, ask if you don't know, agree if you're asked for a favor (like taking down someone's targets or loaning your stapler), talk to the ROs, etc. Mainly, though, it's really a matter of noticing how people carry themselves, how they talk, how they dress. That goes for a lot of other things, too.
In fact, you could extend that a bit and just note that in general, getting along with any group of people requires a bit of observation and willingness to observe their standards of conduct. Some of the discussion in this thread, while veering off-topic, actually does address this explicitly. There's often a fine line between craven conformity and respect for the way other people do things. The wise person will grasp the difference.