What is the best process for buying an Account to avoid getting scammed?

I want to buy an Adword account, however I don't want to get scammed. So how do most members who buy accounts avoid getting scammed?

I don't want to send someone $100+ before I know the account works. So what is the best process?

Any input is greatly appreciated

Check his reputation and also say for him that you need at least 10 accounts to se does it work's.