Yup - the best way to do it is to dive right in... there's no better time than the present.
My first time I was running all season tires, stock eveything except brakes, good pads and crappy fluid. Wound up having the time of my life -- and boiling the crappy fluid
Brakes matter more than anything else!
IME, NASA is a great organization that runs /w excellent instructors at a reasonable price. You might get more seat time elsewhere, but often at the cost of instruction. Plus, honestly, you get enough w/ NASA for a novice (your concentration will wear you down more than you think). For your first time, I might recommend taking your car to a shop to get it teched (tech forms are available at the NASA website) just to be sure (unless you really trust yourself).
Aside from that - go register! B/c after your first weekend, you are going to kick yourself for not having done it sooner!
Mark