You're going to need a licensed contractor if you're planning on using a construction loan. You also going to want to be prepared to move froward in a sequential manner. I do not recommend putting in a foundation and letting it sit there for an extended period of time.
Depending on your skill set and experience you, as well as the constraints of your site and any pertinent zoning considerations, the first step is to site your home giving thought to things such as view, the path of the sun, any significant trees or existing landscape features you may wish to preserve, elevation features, etc. If you are going to need a septic system then depending on where it's to be located you may want or need to have it done first.
It's really important that you understand the entire building process so that you can sequence work properly, failing to do so will cost you both time and money and can be extremely frustrating not only to you but to the sub contractors having to do the work. You also really want to work on your house plan while it's still in the paper stage. Moving walls, and making changes in print is relatively easy and inexpensive, while making changes in the field can cost some real money.
Look around and find yourself a licensed contractor that has a good reputation who is willing to work closely with you and perhaps even allow you to handle some of the tasks that your suited for.
Building a home can be a very exciting and rewarding experience but it can also become overwhelming particularly if it's not what you do all the time. I wish you the best of luck and hope you end up with a home you really love.