Weed the area of ground around the hedge.
Apply a slow-release shrub fertilizer to the hedge before pruning.
Cut off a healthy portion of the older branches around the entire hedge. Remove long branches that are protruding from the body of the hedge. Cut the branches off as close as possible to the ground and central stem. Avoid cutting any branches that are supporting inner growth. Avoid removing any newer growth. Remove enough outer growth that light can penetrate the inside of the hedge.
Prune smaller stems and shape your entire hedge so that it is larger in diameter on the bottom and smaller on top. Always cut just above places where the stems split in two. Avoid cutting in the middle of a stem.
Apply a slow-release shrub fertilizer to the hedge in the spring following the pruning.
Remove another healthy portion of the older stems the following season. Reshape your prune so it is larger on the bottom and smaller on the top. Over time your hedge will regain healthy density and you can give a more definite shape to your hedge.