Fall pruning in Seattle is appropriate for shrubs that need no protection from the coldest temperatures. The Pacific Northwest has mild winters with occasional blasts of arctic air that send the thermometer down by 10 to 15 degrees, freezing shoots of the more tender plants. If in doubt, wait until early spring to remove branches. Also, wait until fall has truly arrived, October or early November, before pruning. Done too early, pruning will force out new growth that will be killed by frost.
Pick out the longest branch you want to remove and follow it down inside the canopy of leaves, below the intended height of the shrub.
Cut the branch with sharp pruning shears just above a leaf node, the place where you see a leaf scar or leaf blade. Never cut more than 1/4 inch above the node, which could kill the stub. Continue removing long branches until the shrub is reduced to your satisfaction.
Thin branches from the inside of the shrub, if you wish, to a more tree-like outline or if less shade is needed beneath it. Work from the trunk outward, taking off the largest branches first. Remove up to one-third of the smallest shoots to give a more open feeling to the shrub.