When having either a business or personal relationship with a subject there's a few things to keep in mind:
You can request an article
It's improbable when having a conflict of interest to write in a way that doesn't favor the subject unduly. However, you can always request the article be written by someone else. This will prevent you from introducing an intrinsic bias into the article, since a neutral party will be writing the article.
You can also request edits
Much like requesting a neutral party to make an article for you, you can also request another editor to make an edit on your behalf. More information on how to do so can be found here.
Stay transparent
Be open about your connection with the subject. There are many editors on Wikipedia, and it's likely you'll interact with them in some way. Being transparent is a integral step in having other editors help you with your article.
