Agree with Coilover -- those movies shoots can be long, boring days, but the chow is great ... well, except the one we did with Discovery ID -- their idea of catering was Papa John's Pizza... still, not too bad.
But getting hooked up in the first place is a matter of timing, being in the right place, etc. Our "picture car coordinator" that we deal with mostly finds her prospects mainly through contacting POCs in the various clubs in our area. After that, once you get cast (or your vehicle) the first time, and you demonstrate that you are dependable and good to work with, follow-on gigs come along. The TV and movie shoots seem to have standard rates that are somewhat location dependent (I think). Movies pay better than TV shoots. I haven't done a commercial, but I think they may be best of all, depending on what they need. A friend did a major shoot for a pharmaceutical and that was a very nice pay day for him (Mike B might be able to corroborate that as he knows him, too). Another one of our 'Bolters had his truck (1st year GMC pickup) used in a GMC commercial and they treated him very well (sent an enclosed semi trailer/car hauler to pick up his truck, etc).
Here's his story
