How do you protect yourself from unethical contractors?

[Nick Macklin]

I haven't personally encountered any issues yet but I was reading some stories of people that have gotten ripped off by contractors and began to wonder how some of you protect yourself from unethical contractors?  This is especially important when you are an out of state investor like me and so many of you.  While I was reading the stories of people putting the initial payment down and contractors essentially asking for more right away after doing nothing and/or just walking away with a large chunk of capital.  

I have pretty much only signed the estimate and then come to some kind of agreement on the draw structure.  Should I be doing more?  I've only used 2 contractors and I have had good experiences with both even though 1 was far too expensive.