I like to customize EVERYTHING I own in my office. It's like I just don't like anything to be the way it was when I bought it, everything has to be made more personal. I like to do little collages and such on the covers of my sketchbooks, mostly for decoration but also so I know at a glance what the contents are. I buy the same brand of sketchbook every month or so, which means they'd all look identical otherwise. And since I own shelves and shelves of sketchbooks, I can't flip through dozens of books looking for one series of drawings.
This doesn't mean other, non-related things don't end up in the books, but I can usually tell which ones are where by remembering the time frame the main drawings where done in.
For my Ringmaster Alice recent sketches, I made an RA book cover for a new sketchbook. On the left is the original cover, and on the right is my custom one. I spraypainted the cover white, then did a lot of doodling and pasting. I like to do these freestyle patchwork covers that are more about my thought process at the time, not just a pretty fancy illustration. I also like to use a lot of blown-up photocopies because I love how photocopied pictures look when they're enlarged and attain little artifacts and other blurries.
The whole cover I tiled with playing cards pasted on, then scribbled over them with markered checkerboard, a queen card in the middle (the queen of hearts is the opposition to Alice and thus this is sort of a representation of a "Wanted" poster, or of Alice's hatred for the Queen and her wanting to replace her.) Up in the corner is a favorite quote of mine from Machiavelli's The Prince, and then an enlarged photocopy from the original Alice book and colored in with markers a bit. Finally a title done in Word and printed out.
The quote in the corner says, "Upon this a question arises: whether it be better to be loved than feared? One should wish to be both, but because it is difficult to unite them in one person, it is much better to be feared." It's paraphrased and taken from instructions by Machiavelli to a hypothetical ruler, and reflects what I think Alice's thoughts would be on the subject in my story.
I'll go on adding little scribbles and things as the project goes on...I think the cover is really as important as the sketches within.
On the right is the first inside sketch, of the Queen of Hearts...all the drawings have piecemeal quotes from the book that I felt suited the characters in my mind. They're not really the most popular or well-known quotes (The Cheshire Cat's is not the "We're all mad here" quote), but they are the most suitable for inspiration for their personalities.
A sketch of the Queen of Heart's castle is on the end.
You'll notice my book is decorated upside down. I prefer to draw left-handed, so my sketchbooks go right to left and are upside down so the spiral doesn't get in the way of my hand