T

THEIR, THERE, and THEY'RE
Wrong: There looking over their for they're dead granny.
Correct: They're looking over there for their dead granny.
Tip: They're is a contraction of they are. Here and there are spelled similarly. What's his and hers is theirs.

THEN and THAN
Wrong: If D's are better then F's, than I graduated from medical school.
Correct: If D's are better than F's, then I graduated from medical school.
Tip: Either way, God help us!

TRY AND
Wrong: I will try and remember this.
Correct: I will try to remember this.
Tip: Thank you. Please do.

TO, TOO, and TWO
Wrong: To bad these too girls don't want two dance with us, Gomer.
Correct: Too bad these two girls don't want to dance with us, Gomer.
Tip: Can you blame them, Jethro?