>>Lock the scope of the assignment in writing before beginning the project. Require change orders for any, and I mean ANY, deviation.

AMEN! In fact, this is VERY important on the FIRST attempt.

The key is to make a super concise spec that everyone signs off on first (paid for, of course). I emphasize BEFORE signing -- in writing -- if there's something you don't see here, it is NOT in. Period.

Anytime they think of something else, I say 'Put it on the Phase 2 list'. I'm pretty adamant about it. If they realize there's something critical they missed, we stop the project, I get paid in full and they re-do the spec and a new $$$ figure is hashed out.

If you give the SLIGHTEST bit on this, it opens the door to 'You allowed a slight change before, and this second change isn't any more of a change than the first.' Which leads to 'This THIRD change is no more than the first two ... ' etc.

If they protest, I ask them 'Do you mind if we up the rate by $20 an hour?' If they say yes, then I remind them if they don't want ME making changes on the fly to the spec on the things that concern me, they shouldn't either.

The REAL key here is good self-esteem. If you are confident that you're the best person for the job, you can talk to your clients like fellow human beings. Not as a dictator, but not as a 'Yessir' person either.