Students want to know what they are buying and what they will get for their money. If you tell them that you charge $25/hour, they will understand what they must pay you but nothing else. How many hours will they need? How often will they meet you? What happens after the first hour?
If sell your services for $25/hour, you will get $25. If you want another $25, you will need to sell your services again, either to the same student or to a new student. That's a lot of work for $25.
You can turn your service into a product by creating a package. Instead of charging $25/hour for "tutoring," charge $200 for an "eight-week learning program that includes eight 60-minute, one-to-one, weekly tutoring sessions."
If you make your service into a product, you will make more money, spend less time on planning, and grow your business more quickly. More importantly, your students will know exactly what they are getting for their money. They will be willing to pay you more because you are offering something of value that they can clearly understand. They will also be more willing to pay you in advance, which will keep them committed to learning and attending sessions.