So... I'll be honest... I haven't completely mastered the skill of behavior management. Often, in my class, there's a lot of noise. There are a lot of kids talking, water bottles being crushed, pencil tapping, and students not facing where the lesson is taking place. I give out warnings and 5 minutes out of their 10 minute break.
Interestingly enough, simply looking for students who are paying attention, making eye contact, and saying "Thank you so-and-so for quietly facing this way" is what locks their attention on me. Right after that happens, other students start following suit... and then, other students follow suit, and so on until mostly everyone does it. It doesn't have a lasting effect, but it is generally an easy way to redirect the attention of students as they get distracted.
I'm trying to incorporate praise more often into my instruction to get students to, for example, raise their hand and be called on before they blurt out. Recently, I tried to praise students who did that and students who worked quietly while working independently. But, it wasn't as effective as when I praised students for putting their attention on to the lesson at hand.