I have been learning tax liens the hard way.
First I read Profit by Investing in Real Estate Tax Liens: Earn Safe, Secured, and Fixed Returns Every Time by Larry B. Loftis
Then I started reading Georgia Law (http://www.lexisnexis.com/hottopics/gacode/Default.asp)Start... with Title 48 read and cross reference.
I can do almost all of my house research online from county websites, goggle maps, court records, and public notice papers online.
Hope to get my first one within next 12 months. The first is the hardest.
Best advice read, read, read. I have few GA links if anyone wants them.