All these planners just waiting to be decorated. Most of us find the one that fits our lifestyle, and either store away the others or give them to someone who can use them, but before that, we've probably collected hundreds of sticker sheets. Since all these planners take different size stickers, you may have accumulated several notebooks full. (In my case, it was plastic bags, boxes and drawers full).
Then...to make the situation even crazier, we learned that people were making stickers that you could download and print yourself! Oh my! And an awful lot of them were free! Absolutely free! And who doesn't love free??? Now, a reasonable person would factor in the cost of the ink and sticker paper or printer paper and double sided tape or glue sticks. But when you are addicted to planners, who is reasonable??
Anyway, the point is that stickers are plentiful, and if you are storing them physically, it works better if you have a system. (Yeah, I know it would work better for me, too, but old habits are hard to break.)
But the good thing is that you can keep them out of sight. No need to print the stickers, because you will use them in their digital form. No need for notebooks, plastic bags or drawers to stuff full of your Michael's and Hobby Lobby purchases. You can store them online, and you can sort them into file folders that help you keep up with what you've got.
I highly recommend that if you don't already have cloud storage, sign up for a service soon. Dropbox, Google Drive, Box and OneDrive all offer free storage.
When you get stickers online, whether free or bought from Etsy or other shops, some will be complete sets, and some will be sheets with a repetition of functional-type stickers, perhaps in different colors.
You probably want to separate kits from functional stickers in order to find them easier.
My suggestion would be to have a hierarchy of folders
Start with a folder called something clever like, say, "Planner Stickers."
Make a subfolder for Sticker Kits and one for Functional Stickers. You might want a category for digital washi tape.
Make categories for each one and create a subfolder for each category, such as "seasonal", "whimsical", "holiday", or however you want to categorize your sticker kits. You can even have more subfolders to categorize them further. Do the same for functional...you might want to divide them into "household", "cooking", "hobbies." You know what your life is like, so choose which ever categories work for you.
If you like to post pictures of your week "before the pen" or even "after the pen", you will probably want to credit the designer or shop. Some people like to put all stickers from a particular designer in a folder. I have folders for Monica's Marvels, Victoria Thatcher, My Planner Envy, and others that I use regularly. I keep all the stickers I design in another folder so I can locate them easily. If you don't want to separate those, be sure that they are identified in some way. Most will have the designer's name or shop on the sticker sheets.
It may take a little time to get everything organized like you want, and you may actually find yourself using more than one cloud storage for any number of reasons. But the more you can consolidate and organize, the easier time you will have finding the perfect stickers for a particular week.