A main frustration I have is with sorting. My snippets are personal use, so I don't share (I'm selfish that way I guess). It'd be great to have sub-folders, from just a visual open/close perspective.
While I'm not into sharing my own, for sharing, I'd imagine baby steps. Just make it initially if the root folder is shared is everything inside (subfolders included).
Naming conventions only go so far. We also use right-click a lot, then select the message. A drill-down folder -> subfolder approach would help there too.