It's pretty cut-and-dried these days.
Arco Smog check stations are plentiful, and there's a JustSmogs close to you in Huntington Beach where I always get mine done.
I think I paid ~$50 there last April, but most everywhere is close to that. Once your car passes, just head to the DMV or go online to register - your info was entered into the system by the Inspection Station.
Chances are your car will pass without issues unless you're burning oil. I've always heard that you need to stay away from the mechanic/smog test places as they always love to sell you something to help you pass.