There is only one lesson to be learned from Baki the Grappler. That is trial by combat. He puts himself through horrific and violent challenges to fight his way to the top. Who in the world would let their young teen do this? We have no idea, but the lesson here is fight, fight some more, fight again, and then fight one more time. You cannot do anything to get better at fighting that is as beneficial as fighting itself.
Be sure to use proper gear. We cannot stress this enough. Too often are martial arts careers ended because a trusted class mate accidently plants a roundhouse kick in the ear when there wasn't proper headgear to be worn. That student is now partially deaf in one ear and has no balance because their equillibrium is screwed up. Don't let that happen to you.