I've come across the question of what a witch is often on paganspace and other sites, in books, on the net, and just about everywhere else. Some say a witch is niether good nor bad, but that actions speak louder then labels, and still others claim that there are such things as white, grey and black magick out there, good and bad, positive and negative energys, and the intentions of the "witch" or practitioner makes all the difference as to which directions these energies take.
I agree with all of it, as they are all very salient points. But I have to go with what's true for me. So, what is a "witch" to me?
A witch is. What a witch is. This, for me, sums it up, nicely. "Witches", practitioners of magyk, sorcerers, magyk users, etc, these are all just individuals that know how to harnass and use the essense of energy as a means to an end. And since energy is neither good nor bad, is neither postive or negative, but is quite fluid, ever-shifting, and ever-changing based on an individual's intentions and direction the energy is to take, the harnassers of that energy are neither good nor bad, but are simply directing the raised energy to a destination they have beforehand decided upon.
I myself try to keep in mind the harm none rule, but I am ever aware that since energy is fluid and always shifting, my intentions do not necessarily mean that that is how my magyk will turn out. I could do a healing for a friend with the best of intentions, and if she was meant to be suffering for certain lessons that need to be learned, helping her could be the worst possible thing.
It is quite true that the greatest harm can come from the best of intentions, as Zed said, and I tend to always keep this in mind, so I can choose my words in an invocation carefully, keep my mind about me during a working, and keep this in mind in my day to day existence. But, keeping this saying in mind doesn't always guarantee that harm will not come out of my good intentions.
So, whether a witch is anything else or not, she is never perfect (only the Goddess and God are) and what she is is simply what she is.