We've rented our house out. It was a bit of a hassle at first -- our international movers came the day before the tenants wanted to move in -- but they seem to be settling in nicely.
We used a company to find our tenants. They knew what questions could and could not be asked, how much security we could charge, how to do a criminal background check, etc. It also made things easier when it came to getting landlord insurance and when it came to signing a lease. The company charged us one month rent to use their services.
We left a large binder with copies of instruction manuals and warranties on everything in the house. The originals are with my parents, who are acting as property managers.
The big thing is to make sure you can charge enough in rent to cover everything -- mortgages, property tax, insurance and association fees if you have them.