Ignore phrases between subject and verb
The box of chocolates is on the table. The subject is box, not chocolates. Phrases starting with of, with, along with, as well as and together with never change the subject.
Or / nor: the nearer subject wins
Neither the manager nor the staff were told. Neither the staff nor the manager was told.
Indefinite pronouns
Each, every, everyone, nobody and either are singular: Everyone is here. Some, all, most and none depend on what follows: Most of the cake is gone; most of the cakes are gone.
"There is" vs "there are"
The subject comes after the verb: There are three reasons.
Collective nouns
In American English, team, family and staff usually take a singular verb (The team is winning). British English often uses plural (The team are winning).
Frequently asked
Is "none" singular or plural?
Either. "None of the milk is left" (uncountable); "None of the students are here" is standard, though "is" is also correct in formal writing.
"A number of" or "the number of"?
"A number of people are" (plural); "the number of people is" (singular).