Some people are uploading entries with slashed tags, or comma-separated tages, such as Philosophy / Buddhist / Dogen, or Philosophy, Buddhist, Dogen and so forth. This is probably a leftover for some other system that you have may been storing your data in, but the tags in Zotero don't work with this multiple slash system--what you will find when you click on such tags is only the single entry that you used it for. And full searches can't find the individual terms. So, just one tag per term, please.
It seems that this caveat will need occasional repetition.
When you are adding to the bibliography from web catalogs such as WorldCat and GoogleScholar, please be wary of adding the keyword tags inserted by such sites, such as /Buddhism; Buddhism/ Anthropology / Culture; (and so forth). First, the Zotero system doesn't recognize such slash breaks, so such keywords end up being unusable. Further, the keyword "Buddhism" often doesn't have much relevance in a bibliography on Buddhism. You can stop Zotero from automatically adding these tags by going to Actions (the small gear icon in your local Zotero) > Preferences , and unticking the box for "Automatically add keywords." -- Chuck