Recommended by Ali Presley
"EFFECT" and "AFFECT"
"Effect" is a noun meaning result. "Affect" is a verb meaning to influence. Ex.: The new policy had a significant effect. The weather can affect our mood.
"THEN" and "THAN"
"Then" relates to time. "Than" is used for comparison. Ex.: First, we'll have lunch, and then we'll go for a walk. He is more experienced than I am.