[tptacek]

If you're going to consult professionally, take the time to write a statement of work for every project you undertake. If it's worth spending a day on, it's worth writing a SOW. If it's not worth spending a day on, don't do it.

The typical contractual form a consulting engagement takes is a one-time master services agreement that establishes all the terms and conditions under which you'll work (this is usually the client's paper), followed by a series of 1-page SOW contracts as projects come up.

Each SOW specifies:

* That it's being done under the master agreement

* The nature of the project being done (it's to your benefit to keep this somewhat abstract)

* The acceptance criteria, if any, for determining completion

* The pricing used --- here you'd establish, for instance, that the project is being done on a T&M basis, expected to take N days, and that you'll obtain written permission should the project take longer.

You should be doing this on every project you run.