If you would like, you could probably start out in a simple snaffle just to see if that's the type of bit that you both get along with well. If you were to decide you wanted a little bit more refinement, you can get that in a simple, gentle curb bit.
This is almost identical to the bits that I use on all my horses after they graduate up from the snaffle in their training and I have yet to find a horse that didn't like it and ride well in it. The port is high enough for tongue relief but not so high as to interfere with the roof of the mouth. Plus, the shanks swivel for the occasional needed one-rein correction. And they are very short shanks so this is one of the mildest curb bits you can find. Pinchless Low Port Reining Bit - Horse.com