Do you have a standard pricing system for your service? If so, please share the details here.
Prices vary a lot depending on the assignment. As a guideline, I use the Editorial Freelancers Association's common editorial rates, which are posted at http://www.the-efa.org/res/rates.php.
What advice would you give a customer looking to hire a provider in your area of work?
If you are working with a freelance writer for the first time, assign him or her a small "test" job. If the results are excellent, then you can probably expect future work to be great, too.
What questions should customers think through before talking to professionals about their project?
I can work on site in Anne Arundel County. And, of course, I can telecommute.