Question: How should a Hydrangea paniculata ‘Limelight’ tree be pruned?

Here’s a question from a reader: I bought a Hydrangea paniculata ‘Limelight’ tree in the fall of 2012. I pruned it a tiny bit as my goal is to have it grow taller. They say to prune it in late fall or late winter. This year I had a ton of big, heavy blooms, and many of the branches drooped over. I am wondering 2 things: 1) Should I prune back the thinner branches…and, if so, by how much? Will…