Affect (the verb) and Effect (the noun) are interchangeable about one time in a million. Forget about that one time; you’ll never need it. Instead, concentrate on the 999,999 times you’ll be correct by following this rule:
Affect: The cold does not affect me. Affect is a verb.
Effect: The cold has no effect on me. Effect is a noun.
Affect/Affectation: The cold does not affect me, but I pretend it does: it’s an affectation of mine. Affectation is the noun form of the verb affect. Effect has no “noun form” because it’s a noun!
(If you must know about that one time in a million, I’ll tell you, but I shouldn’t risk it: “To effect that change, we had to pull all his teeth.” The meaning of this use of effect is “to put it into effect.”)