To Prune or Not to Prune, that is the question...

Sept. of '08 I purchased a home with well-established plants. The original owner had had a beautiful yard, but after her death, the next owner allowed the cudzu and ivy to overgrow EVERYTHING for three years. I had a crew come in to hack through all of it, and in the process the oak leaf hydrangeas which I didn't even know existed were cut also cut drastically. They came back well last summer, but no blooms. Now it's Jan. and I have tall wooden stalks sticking up. Do I dare cut anything, and if so, how much and when? One plant has stalks 6-7 ft. tall...... Any help is greatly appreciated!!