These were taken from a Readers Digest article (http://www.rd.com/advice/grammar-rules-how-to-sound-smarter/). To get the specifics, you'll have to read the article:
You never mean: preventative
You always mean: preventive
You almost never mean: infamous
You almost always mean: famous
You might say: evoke
You might mean: invoke
You might say: denounce
You might mean: renounce
You might say: uninterested
You might mean: disinterested
You never mean: "Jane, Andrew, and myself are going…"
You always mean: "Jane, Andrew, and I are going…"
You might say: former
You might mean: latter
You almost never mean: neither/either are
You almost always mean: neither/either is
You never mean: fall between the cracks
You always mean: fall through the cracks
You might say: mute
You might mean: moot
You almost never mean: just desserts
You almost always mean: just deserts
You never mean: modern-day
You always mean: modern
You might write: so-called "good grammar"
You mean to write: so-called good grammar
[not sure I understand the above one]
You might say: exuberant
You might mean: exorbitant
You might say: come
You might mean: go
You might say: jealous
You might mean: envious
