There's a massive library out there but you might try:
General : Alan Oken's Complete Astrology, Chart Interpretation, Stephen Arroyo, Astrology, Psychology and the Four Elements - Stephen Arroyo.
Houses: The House Book, Stephanie Camilleri and/or House, Temples in the Sky Deborah Houlding and/or Houses of the Horoscope - Alan Oken
Predictive Work: Planets in Transit - Rob Hand, Predictive Astrology - Christine Shaw, The Art of Predictive Astrology - Carol Rushman
Synastry: The Astrology of Human Relationships, Sakoian & Acker
If you are interested in medical astrology or traditional astrology I can indicate books in those areas.
Also read a good magazine, like the Mountain Astrologer.
The above are by no means exclusive, or the best, they are simply books that I've found useful and I'm continually reading more - I have a massive 'to read' list still to work through.
Try and establish a plan for your reading - don't be a Gemini and flit from topic to topic - be a Capricorn and work to a plan.