Read The Book On Rental Property Investing by Brandon Turner and watch a few podcasts on the subject. Do this and after a few weeks, you should have a good bit of knowledge to work with.
Also, attend local meetups and REIA meetings to speak firsthand with those in your area who are doing deals and pick their brains for advice.
Find out how much you can borrow, start saving for a down payment (you'll need 20% unless you buy a duplex and live in half and rent the other half out), pay down any high interest debt (this will affect your ability to borrow) and start researching the market for house prices, rent prices and areas where you want to buy.