An SEO article writing service can be offered by two different sources; Individual freelance writers, or a company that offers a SEO article writing service. Both can provide the services of eBook writing, article writing, or provide a blog writer, but the following should be considered before you ever buy articles from a freelance source.
A freelance writer is an individual, not a company, who uses online temp agencies to make contacts for contracts. The pros of working with this channel are that you make the contract as the client, and you only pay if you are satisfied with the provided work. This makes for a dynamic source to buy articles, and keeps the majority of control in your hands. Some such temp agencies are oDesk or Elance, which have both been around for several years.
However, the cons of a writer are more numerous. Since the Internet networks together individuals of all countries, there is a possibility that you will be hiring a non native English-speaking writer. Further more, the process of becoming a freelance writer is not very difficult or lengthy, and one individual can literally make dozens of freelance accounts in the course of hours. This compromises the user feedback or rating system on the freelance websites. Also, many writers are on a per project basis, meaning the faster they get their work done, the sooner they get paid, and move on to the next. This can sub standardize the level of quality of the SEO article you planned to use for your web content. Many freelance writers are new to online writing, and still trying to figure out their own style to maximize an SEO article.
In closing, if you are going to pick a writer, make sure to look at their previous clients, their user feedback, and their samples. By doing so you can get a feel for the way they do business, their writing style, and get a heads up on any difficulties that might arise. While freelance writers are an excellent source to buy web content or SEO articles at a price that you feel is right, they are not in the same league as a company that offers a SEO article writing service.