Most writers find it easier to work with a professional writing service. The reason why is because such service have writers that are experienced in the field. They usually have vast experience in their chosen genre or subject matter. Such writers will be able to provide high quality work in a timely manner.
In order to find such services, you just need to do a Google search. You can either contact a writer directly or inquire from them via email. Keep in mind to choose a writer who is reliable and has done work for similar products and themes in the past. Asking around will help you weed out those who are not reliable.