1. Neither/nobody/no-one/none (arguably)
These all take a singular verb. So: “neither of them is going out”, not “neither of them are going out”.
2. One out of 10…
This also takes the singular verb. One person (out of 10) is doing something; all 10 people are not doing the activity.
3. One of those people who…
Counterintuitively, this takes the plural verb. For example: “He’s one of those people who sleep standing up.” There are many people who sleep standing up; he is just one of them.
4. Less/fewer
“Fewer” is used to refer to something you can count; “less” refers to something you cannot count. So: I have fewer sugar lumps than you have. But I have less sugar than you.