Accept vs. Except
Accept means to take or receive: I accept full responsibility for the outcome. Except means not including: I will take everything except the potatoes.
Your vs. You’re
Your means belonging to whoever you are referring to: Your dress looks nice. You’re is a contraction of the phrase “you are”: You’re going to have to hurry it up if you want to be on time. Your is often incorrectly used instead of you’re.
Lose vs. Loose
Lose means to misplace something: Whatever you do, don’t lose my grandmother’s earrings! Loose means not tight: Those jeans are way too loose for you.
Affect vs. Effect
To affect something means to have a change on it, which creates an effect. This one is particularly tricky for most people. Affect, when used as a verb, is to act on or impress. When used as a noun, affect is a feeling or emotion. Effect, on the other hand, is a result and means something that is produced by an agency or cause. Here is an example of the two: Taking antidepressants affected his mood; more energy was a side effect of the medication.
There are many similar pairings that can confuse even the most well-read individual. You can always find a correct answer on dictionary.com or in a printed dictionary.