The common ones are in bold.
Effect - "Wow, the special effects are great." This is a noun, and the most common form of the word you'll encounter.
Effect - "He produced a plan to effect change in the company." In this case, it's a verb which means "to bring about". This is much less common than the noun "effect", but maybe easier to confuse with "affect". If you're not sure, either look it up or choose another verb.
Affect - "Violence does not affect me." Verb, and this is the one you'll use and hear and read all the time.
Affect - "He has a weird affect, like a facial tick." This one is different from the verb "affect". It's pronounced differently (stress on the first syllable, "a" as in "dad"), and refers to facial expression and mannerism and stuff like that. If you see this word, you'll know it, because it's completely unrelated to the verb and is always in clear context.