Whether you are looking for simple advice, or have a larger project in mind, I have 2 price levels.
Level 1: $75. This is the minimum fee. It includes anything needed that requires up to 1/2 hour. This generally includes anyone looking for plant ID, garden water feature issues and disease ID. Often, a customer emails several photos of the problem for review. It may also include a phone conversation if needed.
Level 2: $150. This is a per-hour fee. It likely includes anything requiring more than just a few (3-7) photos can solve.
When a customer contacts me, I will need to know what service they are looking for. That info will let me know which price level they will fall under.