When you start a Free Mission, Equip the "Regeneration Tag" to one of your Recovery type Characters(Sakura, Ino, or Karin). (It can be found after completing the "Protected Princess" Free A-Rank Mission) then when you play a free mission, If you're playing as a Recovery Type Character, walk towards one of your teammates, and use the Regeneration Tag. Once used, all allies within Range will continuously recover health until it wears off, and your Kizuna Points will Continuously increase!(NOTE: this will work more effectively if the Allies you're near are poisoned, or have lost some health)
When Battling the False 2-Tails(the one in the Volcano Area) make sure the 2-tails is focusing on attacking you, and run to the opposite side of the Lava pond, and you should receive Zero attacks from the 2-Tails(you won't receive Damage from it) being as it can't cross over the Lava pond. Yamato is the best character to play as when fighting it. Just stay on the opposite side of the Lava pond, and use the(Circle, Circle, Circle, Triangle) combo.(the one that summons the Forest underneath the enemy), and you should be able to finish the 2-Tails easily. NOTE: Also, pay attention to your health bar when attacking the 2-Tails, being as if you're too close to the lava pit, your health will Decrease. So, make sure one of your Recovery Type characters is nearby, so she can heal you once in a while.