For Poms, line brushing with a slicker brush is the best way to brush. I usually start at the bottom of a hind leg, holding all the hair up with my left hand. Then I pull one section down (still holding the rest of the hair up) and brush it out thoroughly; when you're done, pull down another section and brush it. Repeat over the entire dog. Once you're finished, take a comb and run it through her hair; that way, you'll know for sure you got all the mats/dead undercoat.
What is a "pinning up style"? Not familiar with that term.