here i am thinking to buy an full member account but i dont have idea to make a deal and how can i be safe from cheater.
1. Get an escrow to check the account being sold (this is a must).
2. I would suggest that you buy an account only to those who already sold accounts or with trust feedback, rather than buy from an account seller hiding from a Newbie account.
If one can verify the account using escrow then your second point should be an issue whether seller is newbie or trusted member.