Most of my 27 years were as a consultant. Honestly, every time I hear someone talk about what you did, scope change, I ask, "What was the original definition in the contract?" Usually I hear back, "it was just a quote for the job, no contract."
Scope changes aren't scary if you write a good contract. As a consultant, that's truly one of the most important skills, writing a well defined scope for contracts. That way when it changes, you're covered by change order fees.
Surprisingly, I didn't learn the hard way, I actually took advice from other people. Granted, I've learned a LOT the hard way, but not that one.
There's a clause that says the scope of the project is defined in an addendum document, and any changes to that may incur additional fees that must be agreed upon by both parties. There's also a clause that the deposit is 100% non-refundable once I have begun work in any manner, and that I'm not obligated to turn over anything until the final payment has been made. This way they have skin in the game, and can't try to pull a fast one with a huge change expecting me to do it free or lose the contract.
Scope changes aren't scary if you write a good contract. As a consultant, that's truly one of the most important skills, writing a well defined scope for contracts. That way when it changes, you're covered by change order fees.