Magick is driven by natural psychic ability. And it would seem that some people are much better at it than others.
Another impression some people may have about magick is that it can be instantaneous and spectacular -- all the magician or witch has to do is wiggle his/her nose and the other person is turned into a frog. Once again, this is a fantacy from movies and tv. The reality of magick is that is very subtle. Magical results often occur gradually, and when they do it is easy to dismiss them as coincidence or chance. There is an economy of scale in magick, and magick always takes the path of least resistance.
That being said, the structure of a spell is very simple. Usually the spell consists of only 2 to 4 lines, often as a rhyme. For example,
Oh let me see
The Spirit in the tree.
The spell may be recited aloud or silently. Sometimes it is sung as a song.
Regardless of what the spell may say, and regardless of its purpose, the words are not as important as the energy used with the spell. For a spell, like a prayer which it resembles, depends upon the intent and concentration of the practitioner for its effect.
(More to come on this topic.)
-- Phil Hansford, March 2006.