How would you like to design a bookmark? All you need is a spare piece of scrap paper and some colored pencils (glitter, why not?).
Cut the scrap paper so that it is the length of a normal bookmark, and the shape of a rectangle (as best as you can make it–perfection isn’t required). Then, you can begin the decoration.
A good idea might be to get your book-loving friends and do this as well. You can each design a few bookmarks, or get some bookmarks that you already have, and you can host a little ‘trading session’. This is when you and some people get together. You can trade some of your bookmark designs for some of theirs, so that you can have a whole collection of bookmark varieties. You can host this ‘trading session’ periodically, like once a year, once a month, once a week, even. There’s no limit to your imagination!