Emanation points and hues are fun, easy ways to make your power visuals stand out from the pack.  Right-click on any power on your action bar to pull up the customization screen.  It's as simple as using sliders and drop down menus to tweak your looks. (Monk's note: You can also click on the lightning bolt on your action bar to pull up your powers window. Sometimes, the box for color customization is hard to see, but it's in the very top right area of each of your power's individual windows - just start clicking.)