Just to start with, trust comes with dominence, you cannot have trust without being dominent. Just to begin with (because im horrible at expaning exersices, I will let everyone else do that) But make sure your attitude is that you are the boss, no exceptions, and be very confident! You wouldnt trust a timid person to lead you if you were blindfolded, even though your horse isnt blindfolded, they would trust a timid person either. I have found it depends greatly on your attitude :)
If there are no horses in heaven... im not going.