The sun in general:
The SUN is considered to be the most important part of a birth-chart and is the one that is used for simple horoscopes.
The Sun influences the outward appearance and overall personality of the individual in question. The Sun represents the exterior of an individual, and the person that they both are and want to be to others. When reading a birth chart in order of importance, the Sun is most important part, with the Moon being a close second. All other planets are but influences in the areas that they specifically govern. For example: If the Sun's influence says that you will handle your business affairs in one way, and your Saturn influence says that you will handle them in another, the Sun typically (but not always) trumps anything else, with but a shadow of influence from the lesser planet.