Whether it feels natural or not, you should still use the rear brake. Even though the front is probably doing 75-85% of the stopping (or 100% in the most extreme of cases), the rear brake is there for the assist. I've found when riding dirtbikes and going into right hand turns it's best to get the braking done a little earlier in case the foot has to come off the peg for a quick stab at the ground. Years back when I was a volunteer in the Big brother/Big sister program I had a kid that rode with me a lot on the weekends with a YZ80. He never wanted to use anything other than the back brake. His reasoning was that whenever he applied the front, he pulled on the lever too hard and was always over taxing the front tire to the point of washing out. Once I showed him proper braking technique, and showed him how to apply it in offroad settings, the nervousness faded. I suggest riding with someone who experience is far better than your own so they can show you what you're doing wrong and how to fix it. This teacher should have lots of patience so you don't get discouraged.
