For a start, both words may be either nouns or verbs, so let us look at the noun meanings first and then the verbal ones...
1 NOUNS
a. The noun, �effect', is basically the result of an action, as in �Drowsiness is one effect of taking this drug' or �What effect on my career will it have if I fail this test?'
b. It can also mean goods or property, as in �After his death, his effects were sent to his son in America.'
c.Thirdly, it can mean special tricks and illusions as used in films and television, as in �The special effects in Star Wars were quite stunning!' (Neither of the two additional meanings at �b' or �c' is likely to be confused with �affect'.)
d. The noun, �affect', is normally used only in psychological jargon to mean the emotion lying behind actions as in �The dream process is an affect mechanism.' (As such, you can more or less forget the noun, �affect'...unless you are a psychologist, of course!)
2 VERBS
a. The verb, �effect', means to produce, accomplish or bring about, as in �By her ceaseless campaigning, she eventually managed to effect her husband's release from prison.' So, Effect has to do with the End result. Notice the two capital letters �E'.
b. The verb, �affect', means to act upon or influence, as in �The illness affected him in a variety of ways.' So, Affect relates to Act upon. Notice the two capital letters �A'.
c. It can also mean to make a pretence of, as in �He affected a Scottish accent in order to befriend her.' (This additional meaning is unlikely to be confused with �effect'.)
Confusion is likely to arise, therefore, only with regard to Paragraphs 2a and 2b...ie when the words are used as verbs. To avoid problems, remember the matching capital letters.