In general I believe in practising by playing songs that require specific skills that I want to enhance, but recently I read about using the pencil between the lips technique to strengthen muscles as well as doing "zips" going through the range of the instrument by starting with a very open embrouchure. The former I practise with a pencil at work while no one is looking, and the latter I practise with the riff from "A Night in Tunesia". Anyway now it feels like there is too much muscle in my lip, and I can't get a decent vibration from them, and further more I can't seem to get a good seal on either. Any suggestions. I am using a yamaha 11C4-7C. I feel like I need a larger mouth piece to fit my lips in the cup.