This is the most important step of all. You must manage contractors as if they work for you because they do. If you don’t want them tracking mud in your house tell them politely to take their shoes off when entering your house. You probably wouldn't allow your kids to leave trash in your yard so why would you let your contractor? If you don’t like the way something is done, insist that your contractor redo it because you will be looking at it for years and if you have to redo something later it will be very expensive. If they understand that you are managing the project carefully and that you care about quality they will be far less likely to cut corners.