Hire an architect. He should be able to guide you as he submits the plans to the city--assuming your city or county requires that. And get qualified for a construction loan to convert to a mortgage so you can start as soon as the plans are approved.

Some builders have stock plans you can purchase and follow their building steps but you can only make minimal changes. It could work if you don't have much 'unique' design requirements for the house.

Talk to the bank that will be financing your project. They will have some requirements and limitations in order to be able to be financed. Then talk to an architect who is familiar with local setbacks, height and hard surface limitations that will need to be taken into consideration during planning. And get rid of cable, nights eating out, that third automobile, or anything else that takes awaysaving money for the project. New builds are exciting, but they generally all go over your initial budget.