Be sure to look around and compare before buying.
( ( ( ( Be ( sure ( to ( look around ) ) ) ) and ) ( compare ( before buying ) ) ) . )
(ROOT (S (VP (VP (VB Be) (ADJP (JJ sure) (S (VP (TO to) (VP (VB look) (PRT (RP around))))))) (CC and) (VP (VB compare) (PP (IN before) (NP (NN buying))))) (. .)))
Don't consider and compare before buying.
( ( ( Do n't ) ( ( ( consider and ) compare ) ( before buying ) ) ) . )
(ROOT (S (VP (VB Do) (RB n't) (VP (VB consider) (CC and) (VB compare) (PP (IN before) (NP (NN buying))))) (. .)))