With programming experience you'd probably make a bigger impact using that experience to work on utilities rather than mods, though you might not enjoy that, so it would be missing the point to do that.
I think that the sort of modding teams that you'd want to join (ie. the ones that don't fall apart) are those composed of experienced modders. So it's probably best to get a bit of individual experience that you can then bring to a modding team later.
I'd also suggest that you start off small. Don't go with something that's well within your abilities, but don't go for something too ambitious either. My first attempt was the latter, and it was a lesson in humility.

EDIT: To be clear, I'm not including programming teams in with modding teams, they're a separate thing. By modding, I mean here modifying the game itself. Since you have programming experience, programming/utility teams will most likely happy for the help.