Here’s a test-yourself quiz on commonly confused words: http://public.wsu.edu/~campbelld/amlit/quiz/usage.htm

The results are private, not sent to me; it’s just for fun.  You can find more quizzes and crossword puzzles here:

http://public.wsu.edu/~campbelld/amlit/quiz/index.html

Here are some other resources:

Oxford Dictionaries has a handy list: http://www.oxforddictionaries.com/words/commonly-confused-words

Found on Twitter today: http://english-skills-success.blogspot.com/2014/01/commonly-confused-words-test.html?spref=tw

My retired colleague Professor Paul Brians has a site on Common Errors in English: http://public.wsu.edu/~brians/errors/errors.html

A test-yourself quiz on homonyms: http://www.mhhe.com/socscience/english/langan/sentence_skills/exercises/ch29/p4exr.htm