Using the Waiting Technique for Classroom Management

Since I am not one to do much yelling, I thought that I would use the classroom management technique of waiting to get student's attention during a lesson. I found that it works, where some students do start telling each other to be quiet but after I start the lesson again the talking resumes. My CT advised me that after being silent, I must make sure that whatever I had to say next, I had to give the impression that it is very important. We tried to narrow down a specific example of what he meant by it because I was a bit confused but unfortunately we were not able to come up with one. At one point, when the silent treatment wasn't working, I did tell the class to let me know when they were ready to resume class and when they said they were ready they still were talking to each other so then I added, "if you guys are ready that means I'm talking and you guys are listening". I seemed to capture their attention for a little longer and then for some reason lost them again in about 10 minutes. I am still working on my classroom management skills and looking for any kind of suggestions short of a severe consequence (like handing out detentions). It's not just one student that misbehaves, at times it's the entire class.