In a world where more and more realize that they have an ability to control the forces around them, shielding yourself from the outside world is a necessary evil.  Depending on the way you do it, you can end up cut off from the rest of the world.  If you do it incorrectly, you end up with chunks of shield missing.

There are many ways to shield.  Some of these are less effective than others.

One common method is to imagine your energy crystallized and hardened around the edge of your aura.  This will repel most attacks, but a strong enough one can shatter through it.  Generally, this hurts like a bitch, and can even knock you out.

The second shield method is to consider it a force-field that is movable.  It bends, wiggles, and deflects any oncoming objects.  Things scatter like bouncy balls off of it, launching them back towards the caster.  The way that I visualize this one makes it difficult for me to maintain.  It is too easy for me to see sharp things piercing it.

A third method is a net.  It catches things, the energies sticking to it like a gnat in a spider’s web.  Unfortunately, depending on the tightness of the weave, some things may sneak through.

My visualization method is a tight, hard shield interwoven with an elastic net woven throughout the shield.  This seems to work best for me.  If the hard part breaks, the bits stuck between the net act as the elastic barrier, and the net catches and sticks to the pieces of the shattered shield.

Again, playing with this is necessary.  Knowing that your shield works before an attack is attempted is always the best method.