It is likely that she has been ridden in a snaffle; Most horse have and all horses SHOULD have been broken in a snaffle. Chuck it on, give it a go, and see how she reacts. I'm sure she will behave a lot better for you, as she will have clear signals instead of confusing ones. If she has no idea, then just take it slowly. Use a big, open leading rein to initiate turns, and let her find her way. It shouldn't take too long, and she will be super relieved!
Thanks a lot, I worry about hurting/confusing her...do you recommend a good snaffle bit that won't break the bank? The other horses at my horses pasture are all owned by the same lady and she really doesn't like other people using her stuff, so I'm not even going to bother asking to use one of her bits.
Also, will I need to get a new bridle for a snaffle bit? Sorry I really don't know a whole lot about this stuff.
Do you have a picture of your bridkle? Most bridles can be adjusted to carry either a curb or a snaffle.
A few different snaffles:
Single jointed eggbut. Most common, and I would guess cheapest if you are strapped for cash. Some horses don't like these though, because they have only one join, they can 'nutcracker' causing the join to hit the roof of the mouth. My little arab is quite happy in this bit. The eggbut sides don't pinch.
If she is having issues understanding turning, something like a D ring might be better. The straight side of the D puts pressure on the side of her mouth when asked to turn, re-enforcing the turning aid.
A loose ring gives the bit more 'movement' and allows the horse to have some play if they like it. Only issue is sometimes they can pinch.
The most 'favoured' snaffle would be a double jointed snaffle. The two joins in the middle eliminate the nutcracker effect of a single join. You can get a double jointed snaffle in any of the cheeckpieces above, eggbut, loose ring, D ring, etc. This si the bit I use on my main horse, a double jointed loose ring snaffle. This one has sweet iron and copper to make it more 'tasty', mine is full copper.
I am glad that I could help out. I know I love riding bareback and it has helped me a lot. You can really feel how your horse moves, and you can move with your horse. If you have any questions just ask.
I am an english rider who now after 17 years of riding english (showing, prof trainers and riding in college) I am dabbling in western ... I think that it is much easier to go english to western then western to english.