Don't write about yourself.
Autobiographical articles (or "vanity pages") present an inherent conflict of interest, as it is nearly impossible to write neutrally about yourself. If an article appears to have been written for self-promotional purposes, especially if the subject fails to meet notability standards, it will be deleted.
Users are encouraged to contribute about organizations they belong to: non-profits, sports teams, etc. — even businesses, provided the contributions remain informative, not promotional.