It will be assumed that the student has a preliminary knowledge of the traditional Qabalah. If this is not the case, then please obtain a basic background from the following texts. The Kabbalah or Qabalah is far too vast a topic for me to ever reproduce it here in its entirety with hope for any real accuracy, especially since I don't make use of traditional attributions and methods. There may be some general discussion of basic concepts on this site sometime in the future, but I will be primarily discussing my own personal uses and modifications when I get time.
It is to be remembered that the Qabalah is a system. As such it is a fabricated way of viewing the Universe and oneself according to a set of agreed upon procedures and guidelines as laid out in traditional (and borrowed) Hebrew mysticism. Does this mean that it is useless as a tool? By all means NO. As long as the student realizes that it is a symbolic representation of abstract ideas, and only one representation out of many (infinite others are possible), he/she should have no difficulty making use of such a wonderful, uniquely personal, and evolving tool in practice.
Everyone who makes use of this system or its basic concepts ultimately creates their own version of it. There have been quite a few in the past who have forgotten this and assumed that everything they discovered through their Qabablistic practices was true for all people. Whole religions have been started because of mistakes (and delusions) like this! It has been my experience that the things I learned from working with Qabalistic numerological/Gematric ideas and techniques were mostly truths about myself, with only a few leads to higher truths existing outside of myself. This was not a bad thing. My views on numerology tend to be less than congenial, but the practical aspects of hands-on Qabalistic practice (when used as an astral roadmap) I hold in rather high regard.
I make use of Qabalistic ideas and practices when necessary to assist me to describe or relay my experiences to others so that they might more easily understand by having the information illustrated in such a manner, or by having a common symbolic 'language' of symbols and concepts to start from. Experiences occuring beyond the normal physical reality are often nearly impossible to relay to others when one returns, and it would be very limiting to try to crunch the experience down to fit such a restricted level of reality. Thus, a system (mental model/map) of symbols is necessary and useful in that regard.
It must be remembered that the tool, namely the Qabalah and the Tree of Life in particular, did not initially beget the Experiences (though it can for us now). The initial experiences of Reality in its infinitude necessitated the creation of the tool. The Tree of Life is a symbolic expression of certain aspects of Reality. It is a mental Map. That same information can be expressed in any number of other ways using radically different designs or glyphs. One can use the Tree of Life like a road map and travel paths that are already known if desired, and/or one can expand on the 'map' and travel to uncharted territory. All of reality cannot be condensed down into One system. Enjoy your studies and try not to become limited in your views or 'bound up' in one system of beliefs or viewpoints.
For recommended reading on the Qabalah/Kabbalah, see this site's books page.