Paperwork. No one seems to like it. But a proper paper trail, besides demonstrating to clients that you are a professional, can save your business and more when things go wrong - if you do your paperwork right.
Several software packages have been designed to generate such forms, and most professional accounting packages can be adapted to generate customized estimates, invoices and more. All should include license and terms appropriate for the project. And all are essentially contracts, so be sure to review them with your attorney before offering or signing them.
Important Notice: This is a sample form for illustrative purposes. This sample may not be suitable for your particular circumstances and different agreements or legal arrangements may be necessary depending on your jurisdiction. Therefore, you should not use this sample, or any part, without the advice of competent legal counsel.