Astrology is a complex art and science which applies symbolic meaning to astronomical information as it existed over two thousand years ago when the practice of astrology was first documented in writing by ancient astronomers and astrologers.
Western astrologers use the ancient positions of the constellations and Sidereal (aka Vedic or Hindu) astrologers use current astronomical positions. The two systems are very different, but work equally well.
Astrologers begin by erecting a natal chart, or horoscope, based on the date, time, and place you were born. Today, most charts are done on a computer which makes them very accurate. But, they are only as accurate as the information you provide. Any reputable astrologer will advise you to obtain more accurate birth information or to have your chart rectified if you only know that you were born "around 5 p.m."
Astrologers interpret everything in your chart individually and then integrate it all for you into a picture of you and your life. Interpretations come in many forms: basic insight into your personality; examining specific trouble spots in your life; comparing and contrasting your chart with that of a loved one, friend, co-worker, etc.; looking at career options and financial indications; finding the best place to live; forecasting future opportunities; selecting the best time for a wedding, to start a business, etc.; spiritual growth; and, answering questions.
Most astrologers have a general practice which incorporates a variety of these services, and they may also have some areas in which they specialize such as relationships or careers.
The best way to use astrology is to learn to evaluate a problem on your own, to examine the choices you have to make in order to fix the problem, and then to consult your astrologer to see in which ways the possible solutions will work for you and when the best time is to make changes, take risks, be patient and wait, plan, etc. With all that information in hand, you will possess a powerful knowledge with which to solve your problems, change your life, and be the person you always wanted to be.