As you gain experience, you'll be able to set flat fees for projects based on their complexity, time and resource requirements, and other factors. Many rates can be based on what a company would pay someone with your skills to do the same kind of work in-house. Generally, fringe benefits equal one third of an employee's pay. Fifteen percent is a common premium. You may also want to consider a profit percentage for funding capital investments or future growth, and surcharges for time-sensitive assignments that may require extra effort or rescheduling on your part.
Many consultants also offer discounts for high-volume customers.
Other variables that influence your prices may not become apparent until after you've been in business for some time. Regardless of your method, make sure that you and your customer agree on a price up front, especially if expenses and surcharges are involved. If the customer wants to negotiate, weigh the pros and cons of a lower fee. Above all, be consistent. You may be tempted to accept less money because you need the work, or you want to build a relationship with a particular client.