Think your project through, start to finish. They should help you plan, outline your options, and discuss the improvements you can make within your budget. They should also help you analyze many details such as where electrical outlets should go, where storage room is possible, and many more vital remodel decisions.
Understand your remodel financing options. There are various financing plans available and your contractor should help you determine the one best for you.
Comply with local codes and permits (whether in San Diego proper or alternate municipality). Most reliable contractors will handle the permitting process for you - making sure his work, and your project, meets all structural, electrical and mechanical requirements.
Provide a written contract detailing the specifics of your remodel, including materials, size, color, model, and brand name of products used. Also approximate start dates and substantial completion dates. Prices, terms of payments, warranties and other details that assure the quality of your project should be spelled out.
Is licensed and in good standing. You can check this out for yourself on the California State License Board Website.