Please allow me to import this post of mine from another SE site:
I'll come back and revise it with relevant examples from this site after researching...
Hey Russian enthusiasts! I'd just like to revisit an old issue that comes up sooner or later in every young Stack Exchange site: Plural tags should be the lead tag in a set of tag synonyms.
Caveats
Rather than be taken too literally and have this rule of thumb mechanistically over-applied, let me qualify that English is quirky and sometimes the singular is better.
Some nouns refer to "things" and some refer to "stuff" and some work for both.
If something is "stuff" then the singular tag is probably better even if the word can be plural too. For instance grammar is a better tag than grammars.
Some special phenomena are best expressed by singulars, especially grammar and linguistics terms sometimes. A good test is to try in a question of the form "When should we use (the) XXX?" For instance "When should we use the soft-sign" is better than "When should we use the soft-signs?".
If something is an abstract concept then the singular tag is better. For instance etiquette is better than etiquettes.
If in doubt try using the tag you are thinking of in an English sentence of the form "I like ABC". For instance "I like backpacks" is better than "I like backpack" but "I like beer" is better than "I like beers".
Another test is to imagine you're writing an article or paper on the topic. For instance prepositions is better than preposition and grammar is better than grammars.
The above two tests also apply to verbs. If your question is about some topic naturally expressed by a verb, use these tests to find a way to express it with a noun instead. For instance pronunciation is better than pronounce.
imagine you're writing an article or paper on the topiccaveat. In fact I edited it a bit since I didn't choose a good range of examples.