If you are thinking about planning and designing your own home, then this is the time to do it right, do it your way, and get it how you want it. No more searching for a plan in which the laundry room was a small closet, when you want one that has room for Your ironing board as well as the freezer stand.
If you have a specific idea in which you want the master bedroom you will be in your new home, then you must be the person who designed the home. There are software packages available that will help you achieve Your dream home design.
You can use the software to start design and tweak if necessary to fit your exact requirements. If you start your design with L-shaped living and dining room and then change your mind, it's easy to do. You can print your design and showed it to the Builder or contractor. From there you may have to tweak or time, but it will be your personal design.
There are software packages where you can add furniture and equipment for your design. That way you will know exactly how everything will go into the home is completed.
If you're not into computerized designs for fear of you, then go ahead and do it the old fashioned way with paper and pencil. Get a pad of graph paper and draw out the basic lines of the home you want, add the interior walls, etc, from there you can add Windows, doors, appliances etc. This is the same concept as the computerized version, but needs a bit more on a hand job.