Fight against Pentel - There are lines around Pentel that hold up a chandelier over his head. Cut those ropes and the chandelier will fall on top of him. This is much faster than throwing objects at him.

Fight against Jacoby - Use Jack's Grog Bombs and throw them on the platform..

Fight against De la Vega - When he is near the central mast, he must be attacked at the same time so that he does his combo and damages the mast.

More money - First, upgrade all your moves that you have. Then kill as many enemies as possible. You will easily kill them. Repeat the level, then kill them again.