From science illustrator Kalliopi Monoyios: “3 Marketing Mistakes Young Illustrators Make”. Important: sign your work.
Think of every illustration you make as a potential marketing tool for your next great gig. If someone is moved by your work, they will want to find you. Give them a search term that will be sure to lead them to you instantly: your full name. Heck, these days it almost makes sense to save them a step and sign with your website URL.
A lot of this advice can be generalized. You never know when a piece of your work may get unexpected attention and cause people to look you up. If you haven’t got a contact, they won’t find you.