I played my first couple of games at 35 stones, which most boxes should be able to do.
After you try a few of those consider adding on.
While the game is balanced at 50 stones, 35 isn't that much lower, and since they would be essentially practice games, the lower level shouldn't hurt that much.
Once you've played a few games you can start adding in a few models to increase the stone cost up to whatever level you are comfortable with.
Always remember, the game is about having fun, and as long as you're both having fun, balance is less important...