Tough to do in a town of 30,000.
I'm pretty fortunate. I relocated to a town of 18,000 and it has an orchestra and a
community band. Both have pretty decent numbers and the orchestra's conductor is a gentleman and a diplomat.
I have felt the cold shoulder when first sitting in with these community groups. I've found that many of the old timers are fearful of giving up their seat, so I go out of my way to show I'm not there to take over. Even if they stink up the joint. =)
Makes no sense for them to act like that. Usually, the main reason to sit in with these types of groups is to have MORE people to make music with. You would think they would at least act like they're happy to have you ! That's so crazy !
I've found that hitting one of their performances before joining can be helpful. I find out what they do not have in their instrumentation and show up at the next rehearsal with said missing instrument. After establishing myself as a competent musician who is pretty easy to get along with I chat up the section I'd prefer to be sitting in.
This gives you the chance to find out who the insecure individuals are and make sure you don't threaten their position within the ensemble. I started within the orchestra on timpani and am now principal clarinet - the chair I wanted.
In the band I showed up with my tenor sax. I was asked to play timpani after the first concert with them and moved for the rest of the season. (Some of the brass players who also played in the orchestra snitched that I was a timpanist
) That summer we started up a big band from scratch. I was asked to play lead tenor, but quickly found out that a serious monster tenor player had been playing trumpet in the concert band. I am now 2nd tenor (My improv skills aren't even good enough to laugh at, generally speaking) - for the moment (may move to alto). Meanwhile I got a gig as the tenor player for a local show and when I came to the first rehearsal and had all the instruments called for in the book and then played all the parts at a fairly high level a few shocked looks came my way. They generally used 3 players if there were 3 instruments in a book.
Cut to the chase - 3 years later I am the stage manager and solo/1st clarinet in the concert band. Not the chair I wanted in the beginning, but the 1st alto is very territorial (and weak) so I am not interested in disturbing her. As it turns out the clarinet book is far more interesting and challenging.
It has been an interesting ride so far.