Words containing IE or EI
I before E except after C or when sounding like A, as in neighbor and weigh.

examples: believe, receive, weigh

Consonant preceded by a vowel
If a one-syllable word ends with one consonant with a vowel before it, double the consonant before adding a suffix.

example: hopped, dragged

One-plus-one rule
When a prefix ends in the same letter with which the main word begins, include both of the repeated letters.

example: misspell

Final Y
If a word ends in a consonant followed by Y, change the Y to I before adding a suffix.

example: candy - candies