***
An English rule I'd only followed unconsciously:
Less and fewer are easy to mix up. They mean the same thing—the opposite of more—but you use them in different circumstances (1). The basic rule is that you use less with mass nouns and fewer with count nouns.
And one I perhaps never knew:
Normally, we pronounce "the" with a short sound (like "thuh"). But when "the" comes before a vowel sound, we pronounce it as a long "thee".