How do I effectively punish misbehavior and disrespect from students at an after-school center?

I work at an after-school center, and we have some teens and kids who have behavior problems. Many of our staff are unsure how to handle it, as we are inexperienced in handling kids and teens (we are volunteer workers). We have tried many things, but regardless of what we do, they seem to forget or not care.

What are some effective punishments that we can utilize while also being sensitive to the teens home situations (which are often bad) and learning capapcities? I already have a positive behavior enforcement, a star chart, and they receive a star for doing good deeds.

Some examples of bad behavior:
-Cursing
-Walking out of the building w/o permission
-Running and horseplay (often very physical)
-Telling each other to shut up
-Yelling instead of talking
-Giving nasty attitudes when told what to do (sucking teeth, kicking chairs, and dirty looks)
-Refusing to do ANY work
-Teasing and making fun of others (some have problems with teasing overweight people)
-etc. I can go on forever ):

We have indeed tried many things btw. Looking for something more innovative and effective amongst troubled youth.