Reducing the displacement of the craft, by eliminating excess weight, is the most straightforward way to reduce the wave making drag.  Another way is to shape the hull so as to generate lift as it moves through the water.  Semi-displacement hulls and planing hulls do this, and they are able to break through the hull speed barrier and transition into a realm where drag increases at a much lower rate.  The disadvantage of this is that planing is only practical on smaller vessels, with high power-to-weight ratios, such as motorboats.  It is not a practical solution for a large vessel such as a supertanker.