12 draws is a standard rack. A couple long slings with biners (you can use tape or rubber bands to secure the clip side if you want) are good to prevent drag if the route wanders or if there's a clip below a roof or bulge. They also come in handy for equalizing anchors, prussiking, etc. I also like to have an extra (small and light) locker in tow, esp for the beginning leader if you ever just want to feel extra secure!
Look at the posts for your favorite places. For what to bring, there's usually info on how many draws you need!
"If you can't do something well, you might as well learn to enjoy doing it poorly."
-- from a de-motivational poster, but I find it oddly liberating