This is the most important tip I can give you: Don't start a project that you can't finish! It will cost you more in the long run than if you just hired a professional in the first place.
Make sure you understand the scope of the project before you start. Then assume that it will take a little longer than you think it will, because it probably will. If you are still not sure if you can pull it off, then call a professional. You don't want to start a project and make a mess of it and then have to call in a professional. First you will have to pay them to fix everything you messed up, and then you will have to pay them to complete the job. It will end up costing you more.
If you want to learn how to do the project, but are not sure you can do it yourself, then you could hire a handyman to come work with you on the project. Some handyman services will help you with a project as long as you are paying them for the time they are working with you.
You can also visit our Ask Eli page to get personalized tips and advice for your projects.