C.A.
I just had my first one last Feb and I'm so glad I did it. I love knowing at this point I'm in the clear.
I had the best lady do mine (in Novato) and it hurt, but it wasn't PAINFUL. The best advice I got was don't look down at how flat your boob is :O) I don't have big boobs and it wasn't too bad. The ladies in the waiting room were funny when they heard it was my first time, which helped too. It is about as quick as a DDS xray, once they get your boob in there. They did 4 total on me. The front boob, so to speak and the more painful is kind of under your arm (the part on me that hangs out of my bra).
Someone also posted a question about 1st time mammograms earlier in the year and had over 20 responses, you could look for that one if you don't get what you are looking for with your post.
Best of luck!
C.