To level up, when you get Naruto or any other character alone go to the Forest Of Death. Stay in the little walk way at the beginning of the forest. Get into battles. When your health or Chakara gets low, go to the health pad outside. Repeat this process as long as desired. After you have completed the game, go to the Garra's Pursuit level. Then, go to anywhere there is a healing leaf pad (the one just before you face Garra is recommended). Use the Ninja Whistle to get into battles automatically. The ninja here are strong. If you need to practice or gain experience first,go to the beginning of the Garra's Pursuit level or the Forest Of Death to level up. You can get the Ninja Whistle in the Hokage's Basement on about the fifth to seventh secret scroll. It automatically summons enemies for you.