Affect, as a verb, has two meanings: 1) to act upon or to move. (His words moved the crowd so deeply that many in the audience wept.) His words affected their emotions. 2) to pretend, or assume. (The nouveau riche wench tried to pretend she knew how to act in polite society and failed extravagantly.) Her affectation of the mannerisms of rich people only showed off her new-found money and snobbery.
Affect, as a noun, is a technical term in psychology and psychiatry. It is pronounced with the emphasis on the first syllable and refers to emotions.
Effect, as a verb, means to accomplish, to bring about, or to make happen. (Her hard work and diligence effected a change in the appearance of the neighborhood.)
Effect as a noun means a result or consequence. (There's a new study out on the damaging effects of excessive caffeine on the nervous system.)
The most often used forms of the words are affect meaning to act upon; and effect meaning a result. Remember them this way. The act comes before the result. Affect comes before effect in the dictionary. Her speech affected the crowd, causing quite an effect.