Back to horses... I had a short stint of riding several years ago, then had to quit. A couple of things I remember:
Wear good shoes, preferably boots of some kind if the toes aren't so big they hang up in the stirrups. It helps to have a heel.
Make sure the stirrups are set correctly - adjusted after you get on the horse - so the edges are not rubbing on your ankle (ask me how I know!).
Try talking and schmoozing with the horse for a few minutes - I always thought it was nice to be polite before asking someone to carry you on his/her back!
Remember you're not going to hurt the horse and it needs clear instructions from you as to where you want to go.
Yep, I had one of those "back to the barn" horses - aren't they a riot? I also had one that would RUN down every slight incline. Lucky me, I didn't panic, so the powers that be decided I could have her for my week-long stay at the ranch. It was a challenge, so I stuck it out. We worked out a compromise.
Some friends of ours raise Paso Fino horses - they have a four step gait that is way different from regular horses and a joy to ride - no bouncing. I was really enjoying riding them when I realized my body just was not up to it - weak knees, bad back, etc. I wish I had started earlier so I could have enjoyed it longer. I agree with Sherry, it's a great thing to do for your niece. Have fun - just soak in the tub afterward!
My brothers introduced me to a lot because my parents were just not 'there.' After I'd done the hot air balloon, helicopter rides, glider flights, skiing, barrel rolls in my eldest brother's plane, etc., they thought I was a pretty good sister, just a late bloomer. Always wanted to do a jump with my brother, who was a performance skydiver in the army, but we never got around to it. I am also averse to high bridges and glass elevators - don't know why some things are OK and some aren't.