How to pick a freelance service people already buy
Start from the buyer
A service is a thing a client already searches for or asks an employee to do. If you cannot name the person who would pay the invoice, the offer is still a hobby.
Make finished obvious
Write what the client receives and what they do not. A homepage, a month of bookkeeping, or ten edited clips is a job. Helping with marketing is not.
Use proof you are allowed to show
A sample, a before and after, or a short description of a past result is enough to start. Invented client names are not proof.