Unless you're already a well-known illustrator it can be tough to find work that allows you to earn a living, even with a solid portfolio and professional attitude – in this article I'm going to assume you already have those basics covered. Promoting ourselves is something we need to learn the same way we learn to draw: with a lot of trial and error attempts because no single way works for everyone. There is no clear path to become established. There are, however, a few basic approaches that everyone can rely on.
There are two ways to get illustration jobs: Those that find and contact you (passive) and those that you find and contact (active