To reduce the risk for both parties, I use following payment terms:
For projects( having value less than $1000)
50% Project Acceptance
50% on Final Delivery.
For projects with Escrowed Payments:
40% Payment to be Escrowed at Project Acceptance and Released on Prototype Delivery
30% to be placed in Escrow at Prototype Approval and released at Beta Delivery
Final 30% to be placed in Escrow at Beta Delivery
and released at Final Delivery with all known bug fixes.