Jody gave you some sound advice. I would add to that, budget. The downtown City of Decatur area, which is truly walkable, will get you less house for your money. Location, Location, Location. The City of Decatur has a wonderful school rating and small town community feel with a great little walkable city with some wonderful shops and fantastic restaurants. Fayetteville and Fairburn will get you more house for your money. They are much further to downtown Atlanta when considering a commute (Atlanta has traffic-and I say this as a former New Yorker) and more suburban. Fayetteville also has some great schools.
So, to reiterate what Jody has said, you really need to know your must haves. Number one will always be budget and then you go from there.
I would love to answer any other questions you may have. I too made the move to Atlanta and I completely understand what it is like to move from one state to another. I can tell you that Atlanta is a wonderful city and we have been very happy here. If you'd like to contact me I can be reached at 404-403-6505-Laura Lowry/Keller Williams Realty Metro Atlanta