Contracting your own home may save you money, and it can be fun, but it is a labor-intensive proposition. Hopefully, you do not have to go to work at a regular job, or at least can take 3 or 4 months off, because the General Contractor, which is what you are proposing to be, is needed almost daily onsite.
You are basically a Project Manager, designing a big schedule to coordinate all the different subs to make sure the right tasks get done at the right time, except none of the people doing the work on this project actually are employed by you. Since they are looking for long-term work, will many times lean towards the jobs provided by the other GCís who offer the promise of additional work. This is particularly true in times like these when there is more work than work crews.
Your daily attendance at the work site is also needed to resolve all the unforeseen problems with the design, delivery of materials, permits, inspections, etc.. If you are going to do some of the work yourself, you have to make sure it is done on time so the next project on the list can be started by the appropriate sub on time. Generally, the subs will not be there to help you out, and they will tend to avoid working with someone doing what you are proposing, because they know why experience plays such a big factor in success, and to them it may not be worth it. Basically, everything that CAN and DOES go wrong on the job site is your responsibility.
Okay, so Iím being tough.. Iím just letting you know what I found in my quest to do essentially the same thing. I finally opted to buy an old estate and renovate. Yet, many people do succeed. If you still want more advice, there is a pair of excellent VHS tapes on the subject of contracting your own home. They were produced from the Hometime series (sorry, Bob), and are available from their web site (www.hometime.com) or through many building supply stores. There are also many books on the subject, available from most bookstores.
If you are still undaunted, I would suggest getting an actual General contractor as a part-time mentor. Many people who advertise their services as a general handyman, are in fact retired contractors. Many times municipalities require a licenses general contractor to be part of the building process, so this is a good work-around, still allowing you to save some money. Also, you will save design fees if you pick a home plan from a magazine rather than custom designing on your own. Architectural work can be very expensive.
Read everything on the subject you can find, ask questions everywhere, and look before you leap, thus vastly improving your chances of a more enjoyable and successful building experience.