Just to help anyone looking to test out the waters, I thought it would be a good idea to have a thread about recommendations on where to begin.
What Site: I had a decent poker background (or so I thought) when I signed up for my first account, which was at Party Poker. I'd recommend searching through posts about which sites Hasselquist members like and which they don't (and why).
Depositing: I started by depositing via credit card. Some credit card companies are making that harder and harder, so I would recommend using the online bank of NeTeller. You can make transactions to and from poker sites via NeTeller, which can be set up to connect with a checking account.
Playing: A lot of people start out with the playmoney tables. I only recommend this if you are brand new to poker or brand new to online poker. In my opinion, the actual level of play can do more harm than good so your best bet on learning to play is actually at the "mico-limit" tables. A good way to get your feet wet without getting cleaned out is to start at a .02/.04 limit table. Move up as you get comfortable.
FreeRolls & Leagues: If you have made it this far, you have probably heard talk of freerolls and poker leagues. Search the site for more info on both, but these offer an opportunity to play for cash prizes without risk.