Advice for exercise riding try out?

She's very pwetty :). I think that, at this point in her training, you just need to take it slow. For her and for you and your shoulder. Don't be nervous about the saddle, I only ride my filly (Also a 3 year old) because I can't find a saddle to fit her, but the saddle, uming it doesnt hurt you, should just give you a little extra security. When riding a green horse, reward them as much as you can. Its a whole new experiance for her and so you should appreciate it when she is being good, otherwise she may start to behave badly if you never tell her when she is doing things right... Just a few bits of information! I'm always open to email so do so if you'd like :).