Following is a list of common errors that will make your list sloppy at the very least and can outright confuse your readers.
1. Failure to count
Well, this is pretty basic. If you promise five techniques for doing something, make sure you give five—not four, unless you then proceed to five. Six is right out. (If you need help in the counting—and the importance thereof—consult the Book of Armaments, Chapter II, verses 9-21.)
You would be surprised at how often the headline or first paragraph of a tips piece has the wrong number, perhaps because two similar tidbits were combined, or because the writer (or overzealous editor) got a brilliant idea for another, but didn’t adjust the number at the top. It happens, trust me.
2. Mischaracterization of the items
If your essay is on “8 questions to ask in a job interview,” make sure they’re all questions—not five questions and three statements or imperatives.
“Give three examples of how you’ve solved a workplace problem” is not a question. “Can you give me three examples…?” is a question. If you need to rephrase something for sake of consistency, do so.