Privets are fast-growing vigorous shrubs that are often planted close together to form a hedge. They are vigorous growers that need to be pruned several times during the growing season. Because their wood stays green longer than most types of bushes, it’s easy to prune privet hedges using standard pruning shears. Or you may find it easier to use an electric hedge trimmer to prune your privet hedge into practically any shape you’d like.
Evaluate the hedge and decide what you want the final shape to be. The nice thing about privet is that you can cut it back severely and it will bounce back and grow so well that soon you won't be able to tell it was ever pruned.
Run a string or rope in the hedge as a guideline for pruning. Simply tie it to a branch at one end and run it the length of the hedge. Place the guideline a little bit to the outside of where you want the edge to be, in case you get a little overzealous when pruning and cut off a little too much.
Use a pair of long-handled pruning shears and trim off all the leaves and branches that are outside of the guideline. Use quick chops with the pruning shears and don't worry about hurting the privet hedge; it's very resilient.
(Optional): Use an electric hedge trimmer instead of manual pruning shears. It's like slicing through butter and you can make curves and other shapes more easily.
After you've finished pruning, stand back and look down the length of the hedge to check for straightness. Do any necessary spot pruning and then remove the guideline.