The CRF 230 F is a good starter bike....that is what my wife rides - we started her on a CRF 150 but she out grew that in about 3 rides and having the magic button really helps as well.
My wife is only about 5'5" and the bike is a little on the tall side for her, but she is able to handle it. It is a great bike and is very low maintenance and unless she is going to do her own work on it, that is a huge plus for us guys!
It is not the only bike, but I can recommend it highly.
~The way I ride no need to worry about cholesterol~
2005 CRF 450 X