Over the years I've started a few mastermind groups (teleclass, Skype, or in person), have helped others start them, and have "taught" webinars about them, too.

Weekly groups, that happen at the same day/time seem to be the most helpful. Helps that each week another person is "the leader" -- not really a leader, but keeps the group going forward.

What I can offer you (for free) are articles 2, 3, 4 and 5 on this page.
http://www.marketingwithintegrity.com/?s=mastermind