It is important to be realistic about what your skill level is. Some projects may appear simple enough for the homeowner to do, however many times it can cost a lot more than anticipated if you don't know how to do it, or have limited experience with the project. I have seen many homeowners take on a project in an effort to save money only to end up paying twice as much to correct a mistake due to inexperience or not using the proper tools.
Ceiling fans, installing peel and stick flooring, painting, are all fairly simple improvements for home owner. Again, it depends on the skill level.