When spring starts springing, everyone gets in the mood to tidy up their flower beds. Well, don't be in a rush to do some of the pruning.
Spring blooming shrubs, such as forsythia, should not be pruned until after they flower, otherwise you will be cutting off the gorgeous display you have been waiting all winter for.
Prune tender woodies, such as crape myrtle and salvia, after new growth starts. Then prune the dead wood off just above the new growth. Some years they will be burned to the ground; other years they will have minimal die-back.
Hardy Hibiscus are so late to emerge (May) that if you cut off the previous year's dead wood in the fall or early spring, you may forget where your plant is. Keep the dead stalks to mark your plant and then cut them off when the new shoots sprout.
Hydrangeas are the plants most often mis-pruned. The old wood looks so bad that it just doesn't seem possible that new growth could come out of those stems. But if you want blooms, new growth must come out of those stems. Resist the urge to "pretty up" your Hydrangeas before new growth starts (and never prune in the fall). When new shoots come out of those old stems, cut off the dead wood above the new shoots. Even then, don't be in a rush. The more growth on old stems that you leave, the more flowers you will have. The newer, re-blooming "Endless Summer" types will bloom on new wood, but if you do not prune off the old wood, you will have blooms 1-2 months earlier than if you had pruned them.