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.
See our Books and Photo Business Software pages for more resources.