Affect vs Effect
Quick answer: Affect is almost always a verb meaning to influence something; effect is almost always a noun meaning the result. If you can put 'the' or 'an' in front of it, you want effect.
Affect
Verb: to influence or make a difference to something.
“The weather affected our plans.”
Effect
Noun: the result or consequence of an action.
“The new rule had an immediate effect.”
How to remember it
A for Action (affect = verb), E for End result (effect = noun).
Common mistake
Writing 'the affect of the storm' — results take effect, with an E.