Designing one's own house is quite doable now with modern CAD (Computer Aided Design) software and the Internet.

Architectural CAD automates many of the technical aspects to help a novice quickly begin designing. You can draw a 2-D floor plan then have CAD automatically generate 3-D walls and roofs. Moving a wall is a click-and-drag. Adding a window or door is a point and click. 

The Internet is an abundant source for how-to articles, product vendor info, even direct advice from architects and structural engineers who frequent the architecture discussion forums or newsgroups.

Homework

The first step is to investigate the constraints and regulations of your lot. Especially those regarding the exteriors of the house which tend to be more rigorously enforced. A builder in my area was well into framing when city inspectors found the house violated the front setback by a foot. The builder had to tear down what he had to start over with a new foundation, incurring considerable cost and anguish.

So you'd want to begin with an up-to-date plot survey to have accurate information. Then call the city's construction permitting department to get the setback/easement requirements (how far within each property line your foundation must be) and the maximum/minimum size and height restrictions for your lot.

You should also consult city regulations (zoning ordinances) and deed restrictions (title document, home owners association) for requirements such as placement of garage doors, exterior materials/colors allowed, which, more often than not, have significant impact on what you want to achieve.

You can research the many references on building code and rules but it's not really that necessary. Residential construction isn't that complicated if you follow common practices. If you talk with knowledgeable people (city inspectors, builders) enough, you should get the necessary info. If you have a friendly building inspector, consider taking him to lunches to pick his brain to save time on research and to establish a working relationship where he can spot/correct problems early.

Preliminary design

Once you're familiar with the constraints of your lot, the next step is to get comfortable drawing your design in pencil (still the best method for preliminary or brainstorming work). Your pencil drawings don't need to look great. Just need to capture conceptually how the interiors should be organized, how the exterior roughly looks. Drawing in pencil also lets you practice designing before you get on the computer, so you won't be overloaded with learning to design and learning CAD at once.

If you have a tough time getting started, you aren't alone. To have a strong vision of your design is one thing but to put it down on paper is another ballgame. To not get overwhelmed, you should start out with what you know most then flesh out the other parts as ideas come to you later.

For example, you can start out with an exterior design that you like (e.g, a Saltbox Colonial) to adjust to the lot and regulations. Then go inside to lay out the rooms you have most ideas about (e.g, living room, kitchen, master suite), then go back outside to see how the exterior needs to be adjusted. Repeat the inside-outside process to add other rooms you require. Do this many times over until you have an exterior you like that can accommodate the interior spaces you require. 

Beginner's CAD

Once you generally know what you want in floor plans and exterior elevations, spend $50 or so for a beginner architectural CAD, of which there are many to choose from. The one I recommend is 3D Home Architect Deluxe (you'll see why later). After spending a weekend or so going through the software's tutorials you should be able to reproduce your pencil drawings in 3D Home Architect with relative ease.

You'll find getting your design dimensionally correct and making changes are much easier with CAD than with pencils. You can specify how wide or tall something is down to 1/16". When you move a wall, the adjacent walls/windows/doors move with it, making it a lot easier for a novice to experiment.

3-D simulation in CAD is helpful for visualizing your design inside and out. With 3D Home Architect, you can simulate walking through and around the house you're  designing. You should also take advantage of the software's furniture symbols to place beds, sofas, tables in the floor plans to make sure you allocated enough space for your furniture and living habit.

Make a lot of changes and try as many different scenarios as you can to get the best out of your design. The greatest benefit of designing your own house is you can explore many more possibilities and refinements than a paid architect has patience for. So consider it a labor of love, and go for as many revisions as you can. Didn't Edison say genius is 1% inspiration, 99% perspiration? 

Good books

First on my list is Christopher Alexander's classic book "A Pattern Language" on designing functional and timeless houses. Another good read is Sarah Susanka's "The Not So Big House: A Blueprint for the Way We Really Live " or her website www.notsobig.com if you don't want another mundane MacMansion.

For help with selecting architectural elements, I recommend "A Field Guide to American Houses" by Dallasite Virginia McAlester. If you want to see creative examples of family homes, a good book is "The New Family Home: Creating the Perfect Home for Today and Tomorrow". For the more technical info on home construction, good references are Francis Ching's books, such as Building Construction Illustrated and Design Drawing.

The Internet

A bountiful source of information is the Internet where you can get how-to articles and direct advice from experts. There are newsgroups/forums where you can post your questions to have experts help you. Some of these newsgroups are: alt.architecture, alt.construction, alt.building, alt.building.engineering.  If you aren't too thin-skinned you can try posting your designs on the net for architects and structural engineers to critique. It can get brutal but you have a good chance of getting valuable feedback.

Also use Google.com to search for past discussions on particular topics. For example, you can retrieve all the past postings related to "post-tension foundation", "wood windows", "metal roof", etc. Spend some time lurking in the newsgroups before posting. Get to know who the experts are and the best ways to ask for help in a given group for better success. Other sites to visit are This Old House, and Today's Homeowner's Forums.

Using an architect

Once you've gone as far as you can with the design and the beginner CAD, the next step is to take your plans to an architect to complete the job. Depending on how much work you've done, you can negotiate a reduced fee or hire an architect by hourly (typically $65-100/hr).

You can give the architect printouts with all the dimensions, or better yet, export your plans to the DXF format, a universal CAD format which the architect's software can read, to save the architect (and you) a few hours of reproducing your design in his software.

Draw plans yourself

For the adventurous souls, you might want to draw the construction plans yourself. Look at blueprints done by the professionals to see if you can handle the necessary drawing conventions and formats.

If you think you can, spend $900 or so for Chief Architect which is the professional version of 3D Home Architect. Chief Architect is pricey but it's only a fraction of AutoCad and ArchiCAD ($4-5K) which most professionals use.  Chief Architect isn't as powerful, but it's a lot easier to learn, especially when you're already familiar with 3D Home Architect.

Two other CAD packages you should also consider are Softplan and DataCad. Each CAD has its strengths and weaknesses, and their approaches to drawing are quite dissimilar. I highly recommend downloading each software's demo versions to try before purchasing.

As you go deeper in design, you should get as much feedback from the various construction professionals as you can. Talk with prospective builders, subcontractors, and the local building inspectors (call city hall and ask for them). Each of these professionals has a different perspective and should provide you with good insights. They're generally helpful so you shouldn't have any problems.

To print/plot plans

To print plans, you can go to a local graphic shop (e.g, Thomas Reprographics in the Dallas area) which will tell you how to format your drawings for the plotters they have. They charge about $10 a page which can add up after a while so you might consider buying a plotter or printer.

If you prefer the standard D-size paper (24"x36"), the plotter I recommend is the HP 430D Plotter which retails $2500 (I got it for $1500 buying over the net). A less expensive option is to settle for the C-size paper (17"x22") which you can get an Epson printer (Stylus Color 1520) for about $500. With the C-size paper, your drawings will be smaller (1/8" scale vs 1/4" scale) but it's plenty adequate for residential plans. The Epson printer is also easier to work with than a plotter. If I were to do it over gain, I'd go with the Epson printer.

Have fun

There is much to know in designing a house, but it's not rocket science. Be patient and you'll get there sooner than you think. Frank Lloyd Wright used to say "There should be as many house designs as there are people" so have fun and good luck.