It was through Random Idea English that I came across this resource from the Merriam-Webster online dictionary:
Top 10 commonly confused words, volumen 1 and
Top 10 commonly confused words, volumen 2.
What's the difference between flaunt and flout, and between affect/effect, desert/dessert, stationary/stationery, flak/flack, It's/its, pore/pour, fewer/less, flounder/founder, principle/principal?
Click on the picture below or on the link above and check if you really know the difference.
Similarly, click on Top 10 commonly confused words, volumen 2 for another list.