Really difficult, Trulia, really difficult.
If you've never worked in construction before, then you really can't "do it yourself," you don't have professional-level skills and you're maintaining a mortgage while you learn on the job.
If you have to hire a contractor, you'll be paying retail for the skilled labor and management and a markup on materials.
Plus - in any area where the market is humming along - you're competing with construction pros for these properties, so the ones you will buy are the ones that THEY'VE figured they can't make money with!
So. It's easy to buy an old house, not so easy to renovate it, and there's no certainty that you will sell it for enough to make a profit.