You've been "advertising yourself" for years. Not to sound too LinkedIn-y, but every interaction with a person is an advertisement, and every person is a potential client.
Most freelancers get started doing work for family, friends, or former bosses or coworkers. Having a prior relationship increases the odds of acceptance, and if you are a worthwhile consultant with a decent client (ideally, you wouldn't approach people who you know would be bad clients) it will usually result in a success story.
