A technique that I used to utilize, I called "IsshinRyu Magick" or "Kill the attack." Essentially, one must have a certain point of gnosis of what kind of energy is being attacked by them on a 3-dimensional scale, whether it be of an element, or light/dark, etc. From there, I send a shot to that attack with the will of negation to it, and it is, in essence shattered, unless the spirit invested in the initial attack was greater than my defense.
I suggest this only if you are very adept at cleansings, purifications, and healing magicks. I have another way to put this:
(IMG:
http://www.thelogbook.com/phosphor/summer99/missile6.gif)
Abstractly, "IsshinRyu" magick is sorta like "missle comand": Something is incoming, you shoot it down, pinpointing the attack and descriminating it out. From all things in that manner, debris still falls, so why not make some servitors to clean up the mess? from there, you could commence Healing Magick protocols to take care of ANY damage/magickal infection left, and you should be fine, on a basic-intermediate level.
Also, from there, you can program your spirit to "learn" what you did each time, and keep it "programmed" in yourself so that when that energy comes to you, unless you have a reason to let it through, you have an automated magickal defense system that learns and keeps up what goes on. Overtime, though, this may be draining, if you are under constant attack. That is why it is usually wise to NOT block out the awareness portion (a big mistake!).
This, however, is meant as a desperate resort for those who have difficulty with overall sheilding (like me!)