One of the most important factors DK, (actually the four most important factors) are the ASC/DSC,MC/IC axes, i.e. the cusps of the 1st, 7th, 10th and 4th houses. In almost all house systems these are basic. They are known as 'the cross of matter'. Other house cusps vary wildly between different house systems; and, to choose which to use, comes down in the end to personal preference. That is why I play down the importance of houses (apart from the cross of matter.) There are also rules about which planets are more important, e.g. the Ruler of the Ascendant's sign is called the ruler of the chart. There are many more layers of rules for importance of this that and the other; and to tell you those I know, at this point, will only confuse you and everybody. In a sense, I suppose, the most important parts of a chart are what WE find most important; not what some medi-aeval theorist thought.

chris