Do you use a sketchbook? If you do, is it big? A favorite size is 9” x 12”. They are great, if you generally draw in a larger format.
But I think a smaller size works much better if you regularly tangle on standard-sized tiles. The reason why is because you can turn the sketchbook easily, just like you turn your tile as you draw. I also like the smaller size because it fits in a pocket or my purse, so I always have one with me!