Building the Shield
When building your first shield, it seems rather ridiculous to lock in any negative energies you may be carrying with you currently. Therefore, a preliminary cleansing, as follows:
Stand in a quiet place and center your energies. Visualize a gleaming sharp sword in your hand. Use it joyously, vigorously slicing through the air close to your body on all sides, over your head and under your feet. As you slash, visualize all unfriendly or negative ties being severed and the ends shriveling away to nothing. Do not be specific — this tie, that tie — all unfriendly ties are being cut! Note that friendly and unfriendly ties exist on different planes, so you can damage the friendly ties — although you may be surprised that ties you through were friendly aren’t — and vice versa. It isn’t necessary to do this every time you work on your shields, although a once-a-year cleansing and general housecleaning couldn’t hurt.
Other helpful rituals include: The Lesser Banishing Ritual of the Pentagram; The Middle Pillar; the Kabalistic Cross; any other cleansing/grounding rituals you may be aware of.