I think freelancers work on a risky platform as they are at the risk if the buyer is going to pay or not . If you are working outside a third party website like GAF , elance etc , you must still use an escrow .Escrow.com is the payment of choice for purchases over $500.
http://Escrow.com holds the buyer’s money from the seller until the seller delivers the item. Only then will the funds be released to the seller. This system makes for a very safe, although highly procedural transaction.