Both of these words can be used as nouns, and both as verbs. Aaack! Writers are running as fast as their feet will carry them, forswearing all future use of grammar!

But no, it is not so bad. I stick by my billboard example. If you remember "sound FX" means "sound effects" you'll be right 95% of the time. And the 5% of the time when you'll be wrong -- the meaning of the sentence will probably be weird enough to send you looking in the dictionary anyway, so you'll actually be right 100% of the time!

So, just remember that effect is usually a noun, and affect is usually a verb.

The exceptions are:

Affect can be used as a noun (with stress on the first syllable) to refer to the physical ways humans have to express emotion: "After the stroke, her voice was devoid of all affect." A good way to remember this might be that adopting a given physical appearance to falsely convey an emotion could be called an affectation.

Effect can be used as a verb when it means "to bring about a certain effect." You can think of this as a case of verbing a noun. The most common usage, I think, is the phrase "effect change", meaning to bring about change.

So, if you're clear on the three examples "sound FX", "affect~affectation" and "effect change", you're good to go.

Effect as a noun is a result.

Affect as a noun is something sensory. a feeling, an emotion, or a tendency.

Effect as a verb is "to cause."

Affect as a verb is ALSO "to cause."

Typically, as verbs, effect and affect are interchangeable. As nouns, on the other hand, they hold completely different meanings.

In practice, affect as a verb usually refers to living objects being affected, and effect is usually related to non-living objects.

Affect (noun): emotion
Affect (verb): 1) put on a false show, like affecting an accent, 2) to influence.
Effect (noun): a result
Effect (verb): to bring about or execute.