Begin with the top of the blue spruce and work downward. Remove any secondary leaders and their growth at the base with strong hedge trimmers or a chain saw, depending on the thickness. Thin out top branches so that light reaches into the bush, and remove any horizontal cross growth.
Locate any branches that appear to be dead. Cut off the ends of the branches and look at the tips; a brown color indicates the branches are dead. Continue to cut back these branches until the tips are white or ivory, indicating living tissue.
Trim back the tips of the remaining branches. Look for branches that have sparse or bare growth near the ends. Use hedge trimmers to cut these back to their first plentiful needle growths.