If people are leery, they could always talk to you about what to expect beforehand. Also, if you're in something and you're finding it's not your cup of tea? Reserve the right to walk away, no harm, no foul. You could make that a caveat before the scene starts.
As for generating RP, it's not at all hard to do. Start a playgroup, but have patience. This is what I see most often, when I hear the 'but there's no RP/I can't get involved' line. People without the patience to build something substantial. ie. It took me awhile to get the ARU/Fire Station playgroups up and active on TR.
Also, accept that there's going to be people/groups who don't want to play with you, for whatever reason. I have struggled with this myself. Often times people see one playgroup and think 'Oh, I want to be part of that! That looks awesome!' but the people in that playgroup, again, for whatever reason, don't want to play with that person. Move on. Don't destroy yourself trying to get 'in'. Most times (not always, but often) you'll just end up bitter and drama-ful. Find something else. There's almost always a something else, if you 'lower your standards' (not sure if that's the right phrasing but it's as close as I can come to what I mean).