A strong password should appear to be a random string of characters, not words found in the "dictionary." However, you can combine several dictionary words with names, letters, and symbols to make a good passphrase.
Good passwords are long: Each character that you add to your password increases the protection that it provides. Your passwords should be 7 or more characters in length.
Good passwords combine letters, numbers, and symbols. The greater variety of characters that you have in your password, the harder it is to guess.
Good passwords aren't guessable: Don't use the same password for CoverMyMeds that you use on other sites, and don't use publicly-known information such as your phone number, date of birth, etc.