Join Date: Sep 2009
Location: Cincinnati, OH (USA)
How long have you been riding?
While I agree that in the long-term, getting an instructor is the best idea, there's no reason to waste money on it if you decide you don't like English (although I personally can't see how you couldn't love it). If you have been riding (even Western) for several years, I don't see any reason to not just try your English friend's saddle (make sure it fits!!!) and just ride a little bit!
Start with a lot of walk work. There's a lot to get used to. First of all, your stirrups should be adjusted to about the length of your arm from your fist to your armpit. When steering two-handed, make sure not to pull with your inside rein - it's a crutch that instructors teach beginner riders, but it is really not good - steer with your outside rein, almost like neck-reining.
Depending on how experienced your English friend is, maybe she could teach you for a while? I started out riding with one of my friends on one of her fat old Haflinger ponies, and it was super fun. :)