Join Date: Aug 2009
Location: New South Wales, Australia
No one is perfect, so when a friend teaches you what she knows, she is also teaching you all her faults. Not the mention that there is a lot she could miss. Pretty much all horse owners know a lot about horses, but that doesn't mean they should be teaching.
At a riding school, the instructor isn't just teaching what they have experienced, but what they have been taught to teach. They, if they are correctly qualified, would have learned about a lot methods to use, and things to watch out for and teach.
Additionally, you will be riding horses that are suitable for lessons - where as you don't know what you are learning from your friends horse.
Lessons aren't cheap, but they are much cheaper than horse ownership. I recommend a bare minimum of a year of weekly lessons before considering owning your own horse, preferably more, and preferably more hands on care experience.