Everybody loves stickers! They are fun, and they can also make quick work of providing yourself with visual cues for future planning. Though it may just seem decorative, stickers can work similarly to color-coding; they provide a symbolic shorthand that can save you lots of time in the long run. And yeah, they're fun.
Bundle up and save! Get a bundle of stickers and/or accessories with your planner, or get some swag for yourself and friends.