A gaming store in your area is definitely a good place to start. A lot of them will have games going on, so ask the store manager if there are any games that are accepting new players. Sometimes you might have to wait a little bit, since some DMs don't like bringing in new PCs mid-campaign.
If you want to get a head start, you can look up the 3.5 reference information [http://www.wizards.com/default.asp?x=d20/article/srd35] online for free. I would recommend that over buying a book right away - the first question you want to ask when you're getting in to a new game is "What version are you playing?" There are lots of different versions. 4.0 is the newest, but there's some resistance to the changes, so a lot of people are still playing 3.5 and a lot of people (like my group) have switched over to the Pathfinder Beta [http://paizo.com/store/downloads/pathfinder/pathfinderRPG/v5748btpy84o0&source=search].
Check out what version you're going to be playing, and *then* get the Player's Handbook that follows that version. Also, you want to get yourself some dice. I'd pick up at least 3d20, 5d4, 5d6, 3d8, 1d12, and 2d10 to start. Get differently colored d10s so you can use them as percentage die. You'll want to accumulate more dice as you go along, but that's a fairly reasonable starting package and can handle most initial setups.
The above poster recommends fighter or barbarian as a first class, which isn't too bad. Sorcerer isn't too hard either, that's what I started with. I strongly don't recommend starting with a Paladin, because they're very confusing to a new player (you have to level your horse). Cleric and druid can be tough first calls too.
Fighter/Barbarian's probably good, but if you have your heart set on a caster, I'd try sorcerer over one of the other caster classes. You might also want to talk to your group a little bit and see what everyone else is playing. If you're joining a group that has 5 casters and no fighters, you may want a fighter. If it's the other way around, you might pick differently.
Also make sure to ask if there are any house rules. Most groups have at least a few house rules in effect, so it's good to know what they are before getting started.
Good luck to you.