The best way to learn astrology is through classes. Find a certified astrologer, and truly take on courses. You can read many, many books, and yet at the end of the day be totally confused. Many astrology guilds have teachers, and courses that you can take. If you live in Canada, there is the CAEE group. Also astrology Toronto puts on many lectures at a very nominal membership fee. Be careful with the Internet, as I have seen some very poor information regarding astrology. If you are unaware of that, you will learn bad information 1st.
To find an organization close to you, here is some guilds that may help you. These are the most international and well respected guilds in the world.
ISAR - international society for astrological research-this is perhaps one of the fastest-growing guilds in the world. They have chapters in almost every country. There was a huge new representation from the skilled at the United astrologers conference in New Orleans in 2012. Their certification program is extensive. And if you contact them, they can lead to certified astrologers, who teach astrology.
NCGR - national Council for geocosmic research - very well international established organization. There are chapters throughout United States. In some countries in Europe, as well as Australia. Certification program is 4 levels. This certification program is slightly different than the previous guild that I have mentioned.
Astrological Lodge of London-probably one of the old's astrological guilds in the world. A spinoff from other groups of astrologers. There are education courses that they offer, as well as certification internationally.
Australia has a couple of different guilds. They have reached in a far more uniformed way in how astrology is taught, there is standard that must be passed before they are considered a school. Therefore, most of the schools in Australia are quite solid. However, certification programs may not always be recognized internationally.
AFA American Federation of astrologers. Again another well establish guild. This organization did splinter into 2 back in the 80s. If memory serves me correctly.
AFAN Association for astrologers networking-an international organization for astrologers to help astrologers. They have a very good mentor program. But they do not have certification programs.
These are the most common international organizations for Western astrology. Vedic astrology has her own guilds. This also applies to Chinese astrology, which to my knowledge has no guilds whatsoever.
As far as Yahoo! answers, I cringe. Sometimes when I see some of the answers. I struggle when people copy and paste, as usually that indicates to me, that they did not know how to explain things in their own words. Not all who are here know astrology. So not all the answers are valid. Some are opinions. Some are just bashers and trolls. So, to learn astrology, I would not consider this, then you the best. I have seen a few people who claim to be certified, yet, to claim may have a PhD in astrology tells me they're not certified.
Hope I've given you some insight.