Start with a book such as this to get layout ideas. It's the best place to start.

http://www.barnesandnoble.com/w/southern-living-house-plans-time-inc/1119947272?ean=2940149128167

Start with an architect and a mutual visit to the lot.

Yes, taking on design and construction by yourself is not advised. It is complex even for 1500 sf. Get an architect and a contractor or look into modular homes, not those horrible round domes. There are really sophisticated modulars done by great architectural companies now. Pick up a Dwell magazine, they are usually listed in there. More on the contemporary side though, so not sure what your style is.

Be sure to check with your county on rules and regs on setback from the lake and the amount of impervious surface you can have.
Building on a lake can be way different than on a regular lot in town!

Start with your lot survey. If you don't have one, get one done by a local surveyor. Then, once you have the survey, which will show the building area limitations amongst other things (surveyor can explain these to you in detail), you will know where you can place the house and where you cannot.

Next step is for you to determine what you want in that house. Make a wish list and categorize your items into three groups. Group 1 are features of the house you MUST have (such as lots of windows overlooking the lake). Without the items in group 1 you will not bother building. Group 2 will be items/features that you really want but are willing to sacrifice if needed. Group 3 are the rest of the items. I can get into a lot more detail but that is the overall concept.

Once you have that list bring the survey and the list to a local architect. Find one through friends or other satisfied references. Make sure you and the architect are on the same page as to design, services offered and pricing. Get everything in writing before starting any work or paying.

Now you are well on your way.

Good luck with your project.