Buyers on Amazon and Etsy already know what they are looking for, if you provide them with cheap and ugly designs, they barely leave the chance and left you with bad comments and reviews. These days, you need an edge over your competition and making activity style books will give you just that!
With coloring books, you need high quality, properly formatted files. You need attractive designs. You need the files to be the right size, resolution and of course, you need enough of them to fill a coloring or activity book.