Arrange your financing first. If you are a homeowner, you might use savings or a home equity line of credit. Builders often rely on construction loans, and preexisting lines of credit with material suppliers. Everything else flows from these financial arrangements, so be certain that you have the available funds before beginning any project.
Get the proper permits for your project and make sure that your sub-contractors are licensed and insured. Job sites are frequently shut down for the lack of proper permits, and using unlicensed contractors can lead to fines and litigation. Obtain and keep copies of every contractor's licenses and insurance verification.
Price check and source all of your materials. If a specific place has everything you need, try to negotiate a discount for buying all of your materials from them. Once you know your project start date, purchase your materials and arrange delivery if necessary. Keep in mind that sometimes the best price equals a cheaper material. Investigate all of the products thoroughly.
Hire your sub-contractors based on references or referrals. Ask to see earlier projects and speak to previous clients. Honest contractors will be happy to oblige. Also check their rating at the Better Business Bureau and the local chamber of commerce. Don't be afraid to ask tough questions, and never choose a contractor based on price alone.