I think that the dominant quality (mutable, fixed, cardinal) and element (air, fire, earth, water) should be calculated, it reveals a lot about a person's fundamental approach to life.
The Sun, Moon and Ascendant are quite important in getting a good understanding of personality.
Look for the tightest aspects first to know the most important characteristics in someone. Unaspected planets (by major aspects) tend to go to extremes psychologically and will behave very strongly predictively even if it is an inner planet.
Planets out of bounds (declination over 23 degrees 27 minutes either North or South) will go to extremes in the planet's domain, this can be either good or bad. People with many planets out of bounds definitely make their mark on the world, they are not bound by the traditions of society.
I would look for planets making a close aspect (especially conjunction and opposition) to the nodes and vertex to better understand a person's destiny or fate and special gifts from past lives.
Stelliums in a house are important in showing a life focus and special interest/gifts.
Angular planets are very strong in a person's psyche (especially if near the IC).
I also find the astrological sentence method mentioned earlier very useful in interpretation.