If you learn nothing else about pruning, remember the May Rule. This rule applies to the Deep South as well as to broad sections of the country. If the shrub blooms BEFORE May, then prune the plant immediately after the shrub has bloomed, or while it's blooming, to bring the blossoms inside for arrangements and enjoyment. This rule bodes well for azaleas, spring-blooming spireas, forsythia, camellias and sasanquas, quince, dogwood, red bud, Japanese magnolia, tea olive, winter daphne, English dogwood, and other "blooms before May" shrubs (early spring bloomersin general). In the Deep South, our "month" of May can start in March and end in May proper, so the quintessential early spring bloomers are those to keep in mind for this section of the rule.
If the shrub blooms AFTER May, prune the plant during dormancy, or in wintertime. This goes for hydrangeas (except Oak Leaf: prune those immediately after blooming or during bloom for arrangements), crape myrtles, vitex, roses, althea, grapes (prune on the coldest day of the year), Confederate rose, pyracantha, liriope and small fruit trees.