I'm pretty sure they do have a mac version of pov, but I know nothing of macs, so you're own your own there. Conniekat8's earlier suggestion of looking at postwork is a good one whether you keep rendering in Poser or not. I  think you want your renders a little more vivid and bringing up the contrast and playing with the brightness levels individually, hilights-midrange-shadows, can be a help. You can do that with renders you've already done and see what you think. You can also do the same with your textures before you render, particularly your skin textures, as they have washed out a bit in some of your renders.