What has been the best way to handle behavior problems in class?

Depends on the problem. What are your most frequent problems?

Vaguely I can state that having a clear set of rules and classroom expectations is a helpful groundwork. From there reminders of these rules and removal for one on one intervention of the offending student is good practice. Additionally, praising the student who are performing the way you desire is great! Chronic behavior problems require the inclusion of the parent or guardian. Additional problems may require the dean/principal/counselor/social worker.

George, I agree the best way to handle behavior issues to start off the school year going over the rules and procedures. It's vital that the rules and procedures are reviewed periodically along with clear consequences for breaking the rules. Students should also receive some sort of verbal or non verbal positive reinforcement when they are following rules and procedures. I try to find out the function of the behavior when a student misbehaves. Why are they acting out? What is motivating them to misbehave? For example is it to attain peer attention. The function of the behavior needs to be addressed.

I always try and take a proactive approach to behavior. Make sure you have systems in place to prevent issues. Such as lining up classes by squad lines in order so there isn't any running to get into the line.