25 years of experience as a small business owner here. Always start high, and only lower your rate in exchange for a guaranteed amount of work. Also consider charging different rates for different types of work as part of your agreement. Always get everything in writing, and keep relevant communication.

All I'll say it is almost a law of physics that lowball clients will abuse you, constantly change the scope of work (after all, you're cheap!), and generally treat you like a cheap whore.

Don't be a cheap whore, be a high class and expensive escort!