I use lightning main, so I don't have many tips for you concerning strategy. But here are the characters that I think you should focus on getting:

I'm pretty sure you get Kakashi after playing for a week - in my opinion he's pretty good until you get 3* Sasuke.

I can't remember whether you can get Sakon and Ukon at level 30 or not through instances - if you can, DO GET THEM! Sakon and Ukon are really fragile, but they do a boatload of damage and their special is pretty good.

Upgrade Kankuro to 3*. Personal experience told me that he was pretty good.



I think my main team after doing Team 7 was Lightning main - Kakashi - Naruto - Kiba or something like that but I can't remember really...

Hope this helps a bit