Below is the discipline structure that I use in my classroom. Keep in mind that all situations are different, so this may vary, but for the most part, I stick pretty strictly to the guidelines below.

First WarningFriendly reminder, no consequence   
Subsequent WarningsStrike on the clipboard, note home in agenda
3 strikes in a day        Behavior Plan and loss of privilege    

Typically the problem is solved after the behavior plan is issued. I consider anything beyond a behavior plan to be extreme. Depending on the infraction, I would either have the child call home or send them to the office. Also, there are times when the friendly reminder is skipped and a strike or behavior plan (or phone call/office visit) will be issued immediately (such as outright defiance, fighting, etc...)

To me, discipline is not all about the negative. I also have quite a few positive incentives for kids to behave including:
IncentiveHow to get it! 
Plus on the Clipboard (cancels a strike)Demonstrate OUTSTANDING K4J behavior! 
Treat boxDemonstrate OUTSTANDING K4J behavior! 
Fun Friday    Less than 3 strikes for the week, no behavior plans, negative phone calls/emails
Top Banana    Earn the most pluses for the week
Positive note in agenda/postcardDemonstrate OUTSTANDING K4J behavior! 
Positive phone call    Demonstrate OUTSTANDING K4J behavior!