Service descriptions are like product descriptions. But instead of describing tangible goods, you're describing the services that you provide, including what you do, some basics about how you do it Start by checking out the competition. Search your keywords and look at the pages in the top three spots. What are they doing and how can you do it better?
(Okay, technically you start with keyword research so you know what your keywords are. TBH, we’re assuming if you know you need service descriptions, you know you need keywords and keyword research.)