Write your bylaws immediately. If someone gets in control that is power hungry the group will either die, or struggle for years. A good constitution protects that from happening.
Also be wary of faculty advisors, they need to remain advisors--they should not have any form of executive power and should be re-elected just like an officer (so you can remove them simply by not re-electing them).
As a small group you may have outside forces (university or national) which will try to mold your group into their design. It is important that the group be the design of those who compose it.
If you need some snippets... email me. I wrote our constitution and I was vice-president and chairman of the chapter when it was installed.
-Tony Destro
http://www.tonydestro.com/