One of my favorite quotes:
"We cannot really say that any one factor (sign, aspect, planet, house) in a chart is 'most important', for all four factors constitute a whole and any one of them missing makes for an impossible situation in life as it is on earth. Nevertheless, a source of power is necessary to start a car. In a similar manner the planetary energies indicate the active desires in the individual." -Ken Stone (Delineation with astrodynes)
Each planet represents one of our basic needs for expression. Here you will find links to articles I have dedicated (so far) on certain planets.