What is the best way to mention a word: italics, quotes, or single-quotes (apostrophes)?
Solution 1:
Any of those options will work, but if you refer to words more than once you should take care to use the same convention in each place. Italics seem the best option if you can use styled text, but styles aren't always available.
In American English, it's conventional to place punctuation marks inside quotes instead of outside. There are a lot of situations where that practice leads to ambiguity, though, such as when instructing the reader to type something:
Click in the text field and type "salami".
It's good to know the accepted convention and follow it when possible, but convention should take a back seat to clarity. A typographic convention, such as using italics instead of quotes, can solve the problem by eliminating the quotes, but even then it's not always easy to tell if a punctuation mark like a period is italicized or not:
Click in the text field and type salami.
Solution 2:
This is a really good question. I don't know why you think it's either trivial. Use italics when writing about words as words, or letters as letters (to indicate the use–mention distinction). When italics would cause confusion, quotation marks may be used to distinguish words as words.