Step 1: The Teardown
Holley offers two different kits; one is a basic rebuild kit that has all the gaskets, power valves, accelerator pumps, and other service parts to do a rebuild. The second is a trick kit that gives you everything the basic kit comes with, along with a bunch of tuning parts to adjust for different motor and cam selections. Ours will be going on a stock 350, so the trick kit is not necessary. Depending on what you need your carb to do will dictate what kit to buy, and if you are not sure, call Holley's tech line and they can lead you in the right direction.
Additionally, before ripping into the rebuild, it's a good idea to have a few little containers to hold small parts. And, if you are real serious, there are many books written to help you along the way.