Never let the builder rush you into signing it. If you don't understand it, don't sign it. If you have questions, ask the builder and an attorney. The contract should contain an arbitration or mediation clause. This clause protects you if a dispute arises.
Most states have laws that provide for a three-day right of recession.
If you contact the contractor in writing or in person during this period, he or she must give you all of your money back, no questions asked. Use your money to protect you. Never pay in cash. Use checks or money orders only. Then, link all your other payments to completed milestones.