The home you are planning to build has to fit the property, or at least, to some extent. Keep in mind that the choices you make will effect the potential future resale value of your home. There is lots of room to play with, but you are not likely to place your garage in the back of the home (with a few exceptions) if the only access is from the front. Or if you have a beautiful view from the front, make that the location of your kid's bedrooms and the laundry room and place the living room and kitchen to the back where there is no view.
The next thing to look at is what size your new home can be on your chosen property. The size will depend on the size of your lot and what your local zoning bylaw requires. The zoning of the lot will determine the building envelope, the maximum area of the building footprint. The required setbacks and the size of your building lot will create the area you have to build within. Always a good plan to find out the max lengths and widths your building can be before you start looking at plans.
And then, of course, you will have to consider that certain height restrictions might be in effect. Local authorities usually determine these rules.
There are, of course, many other things you will have to take into consideration when designing your home. The cost of the building will influence most people in how they design their homes.
You have several options here, and the most economical one, and what would be the sensible way to go for most, is to find a stock plan that suits your needs and the lot you are building on. If you go that route, get multiple copies of the plan. 8 to 10 would be a good number.
If you have some time and a bit of building knowledge, you can invest in home design software. There are some excellent programs available for around $500. Not going to name any names here, but there is also lots of software on the market that is useless to purchase. After you finish drawing your home, get a draftsperson to look it over and let him make sure that everything works and all the required information is in the building plan.
If money is less of an issue, you could have your new home custom-designed by a home designer or architect. It never hurts to have a knowledgeable person on your side when building your home.