Rehabbing a Rental Property Using a Contractor

So I agreed to a binding deal last Sunday on what would be my first investment property.  It's a single family home in the neighborhood I've lived in for the past 4 years, and knowing what I know about the real estate market, I think it's a pretty good deal.  I've got the home inspection coming up on Friday, which I'm hoping will reveal a lot about the condition of the house.  Walking through on my visit, I could tell there will be some work to be done (new windows, foundation work, some cosmetic stuff, etc.).  I plan on doing some of the lighter work myself, but I'll be hiring a contractor to do the bigger things like window replacement and foundation work.  My question is, "how's the best way to pay a contractor?".  I haven't settled on a contractor yet, but you always hear those contractor horror stories about paying them a sizable amount up front, then you never hear from them again and they're nowhere to be found. I was hoping the BG Community would have some advice on how to not become one of these stories...