It's ok if you're not an experienced contractor, you just need to know what your strong suits are and go from there. I have a handful of
San Francisco plumbers and electricians on hand at all times for two reasons.
1) I don't like messing with that kind of work, I'm not comfortable with it.
2) It's always better if you can say that you had a licensed plumber or electrician do the work.
But if you're handy and have basic carpentry skills, it should be no problem to do the majority of everything else yourself.