When I began working as an artist and wannabe cartoonist I found work designing T-shirts. I spent about twelve years at this. Twelve... long... years. This was my first regular and semi-regular bread-and-butter. I started as a freelancer. "Contractor" was not a word I knew then. I worked for both big and small companies. Some of them were garage ventures.
Eventually I found regular work full time for a few different companies. While at my final T-shirt company, Sun Sportswear (extinct), I did scads of licensed character art. Garfield was one of the most popular lines.