Ignore any early shoots you see spoiling your Juniper's uniform shape in the early spring and keep your hand from pruning until mid-June. Early trimming can bruise sappy new growth and cause the shape of your topiary to become damaged and unrecognizable. Leaves are tough enough by the middle of June to accept a good pruning. You can prune again in September, if needed.
Simple shapes such as cones and balls that are not far gone from their original shape may be trimmed by sight. Snip with hand-held trimmers for accuracy.
Overgrown ball-shapes should be pruned by fashioning a length of gardening wire into a circular dimension that is held over the plant as you prune. Ensure your chances for a perfect sphere by constructing the wire frame slightly smaller than the foliage.
To restore a cone shape, stand above the Juniper and prune out from the center of the tree. Work around the plant for a uniform appearance. You may also use a wigwam-shaped cane guide by securing three canes on the sides of your juniper and forcing the prongs into the ground. Secure the top and sides with gardening wire and trim with shears to the framework.
Spirals can be re-established on Junipers by working from the top down to the bottom. Start by pruning the top of the spiral all the way into the main stem. Continue trimming your tree by first pruning the upper turn of the spiral, then the lower to create the ideal curvature.