Before you get too involved in designing your own house, make sure you visit your local city and zoning office. Now days, you need to get permission from the government to do almost anything it seems.
You will need to make sure that the house you want to build does not violate any of the zoning laws. You may also need to get permits for things that you never even thought of. For instance. in some places you need a permit just to expand your house or attach a covered awning to your patio.
How do they find out if you have broken the zoning laws or need a permit? They do fly-bys in many cities which compare what the land looked like last time to what it looks like now. If you want to design your own house and build it on your property, it is best to make sure you have everything lined up legally first so that you know what is required of you. You want to make sure you know exactly what you are getting into so that there are no nasty surprises later on.