In a bio, you're supposed to introduce yourself. You should tell the reader a few well-chosen snippets of information so that they can comfortably assess you as a person. Favorite color, hobbies, and pets are good places to start. If you, for example, have a passion for writing and creating stories, don't be afraid to announce it in your bio!
If you're an artist, it is vital that you include details about your craft and background. For example, if you're a writer and have certain qualifications, such as a six-year academic background in creative writing and literature, you should add it in your bio. And if you, for instance, are proficient in a wide range of genres and formats, that's good to include as well.
If you're active elsewhere or are in the business of selling your art, the bio is a great place to showcase such information. To facilitate the reader's short attention span, it might be a good idea to make a list. Lists make you look professional and have a way of attracting attention. Lists are important.