Explain to your future clients how they will benefit from your service, what exactly they will get out of it, and how it will affect their business.

Use bullet points to state clearly what your service includes. Be as detailed as you can be and write down everything that you will do during the course of the service

Let your client know what they need to provide you with, in order for you to complete your service. Background information, accounts, any relevant details, etc.

Point out what will happen once you are done with the service, e.g. how will the metrics change, what will be better in comparison to before doing the service, etc.

Come up with three or more questions your potential client might have about your service. Answer the questions yourself in detail, as if you were actually answering your client's questions.