Contract Killers
Most agents will sell you on their ability to market a property or find you the best deal. Obviously, these are critical basic skills.
Don't forget to ask your agent about their negotiating skills and advice on contract terms. The silliest items sometimes kill a deal. I am talking about terms other than the price. Items such as the earnest money, survey and option period are critical. And, if you enter the world of Non-Realty Items such as furniture, another can of worms is present.
I know of a deal that fell through over a swing hanging in the tree!
Start with finding a property and getting the price right. Then, make sure you focus on other specifics. A signed contract is just the first step.