Young hopefull REI investor with a lot of cash

[Alexander Ball]

I have been dabbling with the idea of real estate investing for a while now. I am intrigued because of the amazing opportunity to get in now while we can buy properties at historically very low prices. Real Estate Investors will be the first to tell you, it seems, that the business is real work, and there are many hurdles for you to start, especially if you are younger.
I have an advantage. When I was 19 I was struck by a motor vehicle, and my case settled this summer -- I am 22 years old with ~90K cash in my checking account. I have a good job for my age at a bar where I can make $300 a week while going to school full time. What I would like to do is spend this semester reading up on REI and shop for deals, and hopefully take a small course load next semester to set up my property/properties.
I would like to buy CHEAP properties that are close by so I can be a very active owner, and also check up on my tenants more often. I am worried about being steamrolled or taken advantage of by contractors, lawyers, my tenants, etc, but I think that arming myself with knowledge would definitely alleviate that.
I have SOME experience with buisness, and I've lived in some rough places before, so I don't think I am going to be a sitting duck. Here is where I need advice: what is the first step? Do I go nextdoor to the single family house that has been for sale for at least a year without any tenants, do I pay for it in cash upfrount, and outright? Do a pay a large portion and make my mortgage smaller?
My credit is basically non-exsistant. I've rented before, and I pay my bills almost always on time. I realize this was very stupid of me. I plan on getting a credit card to use for gas and paying utility bills etc, and two more to keep in a drawer in my house. What else do I need to do that I havn't thought of?