Hi.
I play for some pop artists and on a handful of jazz records.
I hate this answer, but it really is being in the right place at the right time.
I've been working in and around studios for quite a while so I was in the environment already. For the pop stuff, a friend of mine is the bassist for everything on this one particular label. When they needed a drummer, he called me and that was about it.
My only advice is to be extremely flexible, learn things quickly, and don't make stuff up about yourself. As retarded as that sounds, one thing that gets players in trouble a lot is giving the impression that you are something you are not to insure your place on the record.
Jeremy