When a client accepts your quote, we oftentimes ask them the pre-pay the project's full amount before you begin to work. These funds will be held in an escrow account until the project has been marked complete by both you and your client—at which point, the funds will be released to you.
We strongly recommend that you ask your clients to pre-pay for the projects you do with them whenever possible. The only exceptions to this would be during ongoing projects (with high total amounts) or when working with clients from large, multi-national corporations (who follow a different payment policy).