1. Don't try this without seeking professional help
I don't mean a shrink, although that might not be a bad idea.
I mean an architect, at least for major projects. A competent contractor will get everything straight, level, and true; the best have a good eye for design. But leaving all the design choices to the contractor is asking for trouble and if by design choices you think I'm talking about picking out the bathroom tile, you really need an architect.
Ever go to somebody's newly-remodeled house and find quirky unusable spaces, oddly proportioned rooms, traffic patterns that made no sense? Chances are the owners didn't use an architect. That's not to say things will never go wrong if you do hire one, but at least you're improving the odds.