What contract clauses protect against scope creep in graphic design freelancing?

[BrianHG]

I've been freelancing as a graphic designer for a few years, but I've recently run into a couple of clients who significantly expanded the project scope without adjusting the timeline or budget, and my basic agreement didn't adequately protect me. I need to create a more robust freelance contract template that clearly defines deliverables, revision limits, payment schedules, and kill fees. For other experienced freelancers, what are the most critical clauses you've learned to include through hard experience, and how do you handle the conversation about contracts with new clients who might be used to more informal arrangements?