If you have a just a few Moodle questions--or even just one question--I will manage our encounter like a help desk ticket.
I will ask you to supply specific information to help me define your question. If I ask for screenshots or a screen movie, I'll point you to instructions for creating them. I might ask for access to your site so that I can see the problem myself. All of this happens before I quote you a price. It's more work up front, but it's worthwhile.
To protect your budget, when I deliver a quote, it will either be a flat rate or state a maximum number of hours.