1	Protect the health and safety of your family and guests. If your attempt to do it yourself fails, will anyone be harmed? A botched vegetable garden is not a threat to anyone, but a poorly designed or built deck could collapse.
2	Obey all local codes. If you are not familiar with these, consult someone who is. Many projects require a building permit. The local building department can review your plans and let you know whether you need them to be professionally prepared.
3	Stay on your own land. Do you know where your property lines are? If you want to build a permanent structure near your property edge but can't locate your property line markers, a survey might be worth the cost.
4	Be realistic about your time. Will the project take more time than you want or are able to devote to it?
5	Be realistic about your talents. Do you care more about the experience of doing the project than the results?
6	Protect the value of your property. Will your property be altered in a way that it would be costly to reverse if the project doesn't work out? (See "Avoid Major Errors in Taste in Your Landscape Improvements," under Related eHows.)