Searching "Accessories" will return results for anything that can be layered over faces. Example searches in this category are sunglasses, hats, eyes, lips, ears, etc.
Searching "Effects" will return results for all stickers that can be used to add ambience to a scene. Example searches include sparkles, fire, confetti, glitter, explosion, etc.
Searching "Peekers" will return all results for stickers that pop up and disappear. These are especially fun for adding to landscapes and in settings where they can pop up behind a screen or out from a wall.
Searching "Word Art" will return all text-based stickers. Example searches for word art are happy birthday, LOL, OMG, bye, etc.
Searching "Emoji" will return results for specialised emoji sets, which tend to be very popular.
Themes like "happy birthday" and "congratulations" have great content that helps users animate their stories to celebrate big milestones.