Since the last guide was from two years ago and is now locked and slightly out of date, I'd figure I'd write my own, and add a bit to it. So without further ado, I present the Unofficial Image Tagging and Searching Guide.
(Note: When I use quotes once, it is for the purpose of helping to single out a word. If I use it twice, that means I'm referring to a word with quotes around it that I'm singling out. This is because searching with quotes can change the results you get.)
1. Use full names over several shorter names. For example, when someone searches "Twilight", they'll also get results for images tagged, say, "Twilight Sparkle" or "Princess Twilight". So, if you see an image that needs tagging that has Farnsworth from Futurama in it, when you're tagging him putting in "Professor Hubert J. Farnsworth" would be the best and most efficient move. Otherwise, you'll have to do something like "Professor Farnsworth, Professur Hubert J. Farnsworth, Hubert J. Farnsworth, Hubert Farnsworth, Farnsworth". Both get the same results but the first is immensely smaller and quicker.
2. This also applies to certain special characters. ""mlp:fim"" is considered the same by the image search as ""mlp fim"", so tagging an image both would be redundant. The same, interestingly, goes for ""mlp:fim"" and ""mlp: fim"".
3. Be thorough, but not overly. (Example of a failure to do this: the MLP gallery. There's so many badly tagged images it's nearly impossible to find the one you want)
- 3a. If you've seen one before, you'll know what I mean when I say KYM isn't a booru. You don't need to note the color or length of hair, for example. However, details such as what room they're in, what book they're reading, etc. is considered a good thing to add.
- 3b. It's typically considered a good idea to tag every character/book/movie/etc. in an image. However, there is one notable exception. When there are a LOT of something like that in an image, such as here, then it doesn't really help anyone to tag all of them. Very few people, if anybody at all, are going to search several of the games they remember showing up in that image to find it again. It'd just waste your own time when you could be tagging one of the many badly tagged or untagged images on here.
- 3c. And now here's the thorough part. Except in cases like the one mentioned above, you want to tag every character, book name, show reference, etc. Also encouraged are things like weapons, any specific rooms or buildings they're in (such as bathroom or library), and the like.
4. The database tag index is also a good place to start.
5. Now on to searching. The basics of it is that you add a space in between tags if you want to find an image with both of the tags. If you don't want an image to have a tag, you'd place "NOT" before it – for example, if you wanted to find an image that was tagged "naruto" but not "bleach" you'd put in "naruto NOT bleach". If you wanted to find an image that had both "beans" and "chicken" tagged you'd search "beans chicken". For searches that have multiple words for a single tag, you might want to try putting quotes around the multiple word tag. For example, if you were searching for "One Punch Man" and "Genos" you might want to try ""One Punch Man" Genos".
5. Unless you use quotes, you want to avoid special characters. They have various and often unpredictable effects. For example, searching "pokemon+rwby" will give different results than "rwby+pokemon" with no pattern as far as I could tell. Searching "*" will return no images, while searching "." will give you all of them. The only two special characters as far as I'm aware that are useful are "(" and ":". ":" is used in many of the documented search operators, so if you're searching for an image that has that as a tag, title, or entry name, you want to surround it with quotes, or it'll not give you what you want. "(" works as a hidden OR function. For example, searching "pokemon(rwby" returns any images that have pokemon, rwby, or both in the titles, tags, or entry name.
6. Take a look at the Search Operators blog post. They'll help you find what you're looking for.
7. Lastly, two search operators not shown are "nsfw:" and "spoiler:". "nsfw:true" would only search for imaged labeled nsfw, and "nsfw:false" would filter out them all. Same goes for "spoiler:" – "spoiler:true" would find only spoilered images, and "spoiler:false" would filter out all spoilers.