There are several Lillith’s in astrology, so you need to make sure which one you are talking about. The most common is Black Moon Lillith which is a symbol in your chart that is a black crescent moon sitting on a cross. Themes of Black Moon Lillith often go to sexuality in a less than good kind of way. Think of Mata Hari the WWI exotic dancer who was executed as a spy- very sultry and using her sexuality. She is also portrayed in Biblical stories in many ways, most notably that she would not be subservient to Adam, so she was basically kicked out. So Lillith’s placement in a chart often suggests a a betrayal and redemption theme, or coming out of hiding then going back in. The general interpretation would be to look at how you are using your sexuality, in a loving or power-manipulative way. Look at the house placement to see where this energy can take place in your chart. For example, in the 8th house, it could literally be using sexuality for power and control, or to get money from others. Mata Hari had hers in Capricorn in the third house of her chart. Capricorn rules governments and the third house is communications. She used her sexuality to communicate government secrets to the enemy. When the government found out, they executed her (Capricorn rules law)
There are several good sources for information on Lillith. The Europeans have used her in charts for years, so check out Claude Weiss of Switzerland. In the USA, there is Kelly Hunter in the Virgin Islands and Demetra George in Oregon. Both have books that address Lillith. You can also search the UAC Astrology website http://www.uacastrology.com/ to purchase lectures on the topic.