I had been doing more digital, but haven't done it in awhile. Right now, and this could change when I get more into it, I have it all sorted into separate folders.
For example:
>Paper
>>Blues
>>Pinks
>>Polka dots
etc.
I also have folders for:
>Elements
>>Swirls
>>Buttons
>>Clips
>>Ribbon
etc.
Then the alphabets I have in folders by their name and if the name is not indicative of what they look like I'll add a word or two at the end of the name, like "silver" or "bold" and that helps me find what I want a little better. Holidays have their own folders, separated by paper, elements, etc.
HTH!