Without good rider biomechanics you are your own worst enemy whilst on the horse. You think you are communicated one thing, whilst your body is communicating an entirely different message. Learn what your body says to the horse and how to say it!
If you find yourself fiddling with the reins, obsessed with getting your horses head down, fighting with the contact or other issue of contact then get yourself a good rider biomechanics coach. This level of use of reins is incorrect, and says that something more fundamental is at fault AND that your understanding of how 'on the bit' works may be incorrect.