I had mine about 6 years ago. Pretty much what Erika posted; except I drank 2 cans of Monster energy drink afterwards and lay on my back the whole day except for meals and bathroom breaks.
The caffeine seems to open up the blood vessels; I know many who drink strong caffeinated drinks to prevent migraines.

Getting lots of fluids beforehand is great advice also. I only was told to lie flat the rest of that day, and I did as I was told and was fine.

It didn't hurt much at all; kind of reminded me of having dental work done under local anesthesia; pressure and a bit of a pinch but not much more. I also had mine done under fluoroscopy; helped the radiologist locate the spot better.

Just hydrate, lie down and drink caffeine and you'll do great!!

Let us know how it went...