Decide how you wish to bid the job. One of the easiest ways to bid for construction work is on a time-plus-materials basis. This is simply a quote of the total cost of materials plus the cost of your labor. Multiply your hourly rate by the number of hours you believe the job will take. Calculate the cost of materials. Add these two numbers together, and you have your price.
Consider the work involved. Are you capable of doing the entire job yourself, or do you need a helper? Do you need to hire subcontractors? The cost of a job can rise significantly when you need to bring in other tradespeople. Make a thorough list of the work that is necessary to do the whole project, and make certain that you have a good understanding of what you are able to do yourself.
Obtain bids from subcontractors, if necessary, before finalizing your estimate. Calculate the cost of materials accurately by measuring carefully with the measuring tape and referencing actual supplier prices. The substance of a good estimate is in the accuracy of the number. If any part of the job scope is unclear, ask questions until you are sure you understand it. Making bids for a poorly defined project is a waste of everyone's time.
Decide where your bottom line is to do the work. Be ready to be flexible if you want the job. One of the best aspects of an informal bid is that it makes negotiating easy. If the client doesn't like your first number, be ready to explain how you came up with it. Customers like to know what special consideration you are bringing to their job. If you can't reach a compromise, be willing to walk away.