Have you ever used "i.e." when you meant to use "e.g."? I know, I know, it's embarrassing. Luckily, I have just discovered an easy way to keep the two clear in my mind.
I.e. is the abbreviation for the Latin term id est, which means "that is."
E.g. is the abbreviation for exempli gratia, which means "for example."
Remember the letter "i" as "in other words," if you want to impress someone by using i.e.
Remember the letter "e" as "for example," if you feel the need to show your erudition with e.g.
That wasn't so hard, was it?