One of my clients has a 15-20 ft dogwood tree that she wants de-mossed. I've never done this before so I have no idea what to charge (will attach pic). I would assume it would take about 2-3 hours at the most, but I'm not making as much as I should be on this yard's maintenance so I want to make as much as I possibly can with this job. What is a good price for this????? Thanks!!!