How do you price home improvement jobs?

In order to price a job correctly first you must define the limits of work, and determine what quality of person you want in your home. 1)"we are going to repair this piece" 2) we are going to repair these pieces" 3)"we are going to replace this" All three jobs can be different prices, have your plumber precisely quote the work up front in writing, that way there is no confusion at the end of the job, A "fair price" has to be fair to all involved parties , not just what the homeowner EXPECTED to pay, fair to the plumber is a price that will have to cover his expenses, he usually has quite a bit more involved in your job than just what you see in your home,His expenses started before you even called, his liability insurance to protect your home, his advertising cost ( that is how you found him), his phone bill and other building overhead, material expenses, health benefits, drug testing and background checks, professional licensing, these expenses must be covered if he expects to stay in business and give you a quality job, if he does not have these things is he safe to work in your home ?