(Oops, took too long so I'm echoing Keii4ii, but with pictures!!)
The tags for individual episodes do nothing!
( ^ these ones) So I would usually list a few tags that might be useful if an ability to search or filter is ever introduced, but otherwise just use them like alt-text jokes.
The tags for your series technically do pop up when you when you search:
( ^ the ones at the bottom here)
If you do a search for "deaf" you'll see my comic pops up! but you'll also notice that a couple other comics are listed above mine that aren't more popular, that haven't updated more recently -- I have no idea how the search results are organised. So tagging my comic something more common like "dragon" isn't super useful, since it's buried somewhere in 50 pages of comics, with no way to organise those results.
I don't know how much tags help, but there's no way to see what a series is tagged as without actually searching that tag, so the most we can really do is make some guesses about things a reader might think to search for!
