I have been an illustrator since 2014 but after submitting to many publishers and looking for an agent I had no success. Word of mouth is what led me to author Rosita Bird. She needed an illustrator willing to work for free to support an animal charity.
That little book Charlie the Crocodile made money for the charity and sparked interest from an american publisher just starting up. That led to more books being illustrated. I worked with Crimson Cloak Publishing for several years and gained knowledge (if not wealth).
I now work independently on a book by book basis and have self published several of my own books. I still work closely with Rosita. So if you are starting out don't be afraid to collaborate or donate your work to charity it might lead you somewhere new.