I've done quite a few, but not in your area.
Since you're a painter, I assume you'll be showing originals. So your big expense will be framing and hanging - presentation related stuff. The gallery or host for the show should give clear direction about what's required from you in terms of labels for the artwork, what types of hangers are acceptable, how many pieces, what their commission is, all that. I would suggest to anyone starting to show work in physical locations that you get insurance, or at least make sure the gallery has insurance that covers any damage to your work.
I have always turned a profit (sometimes a very small one, but still a profit) at shows I've participated in. It really depends on how many people see it and their response to your work. Ask the gallery how they'll be promoting it, and make sure you promote it online and in real life (postcards, mail them if you have a list, leave them in busy places if you don't) if possible.