If you have VOX walkie talkies, it will help with formation flying. The leader should fly lead and the other pilots should follow his lead. With the walkie talkies, the leader can tell the others on the team when to turn, what manuever is next and when to execute.

It is also beneficial to have the same models with the same engines, etc. There is a group in my club that are learning to fly in formation. We are using the World Models P-51 Mustangs and aren't doing too bad.