The yield of DNA after gel extraction varies from kit to kit. We have had some kits that had terrible yield. But once those were returned and replaced the efficiency got better.

With respect to the technique, You can always elute in smaller volume to increase the concentration of DNA (do not go below 10ul). For larger fragments most kits recommend adding one gel volume of isopropanol before initial binding. Also, ensure that the gel dissolving buffer is yellow. Add 3M sodium acetate (pH 5.0) if it looks pinkish. If you have followed the recommended protocol well and the yield is still poor, scale up the process and purify using two or more columns, because the limiting factor will be the efficiency of the spin column.