Playing is the only way to get your chops in shape.
Long tones....blech.
Do 5-10 minutes of scales/arpeggios to get things warmed up. Play them slowly so that you can hear how EVERY note sounds. This is where you should be shaping your tone.
Don't be afraid to experiment with your sound. Take in more mouthpiece, open your throat, pull down more chin, change the horn angle..... Find where your clarinet sounds the best.
Move on to 15-30 minutes of focused technical playing. If you don't have the Klose Complete Method for Clarinet...Get it. It will kick your butt, and you'll love every minute of it. There are lots of method/etude books out there that are almost as good. Just be sure they're a little more advanced than what you can play now.
Play a couple of short "just for fun" pieces, and finish up with long tones.
The long tones are like cool down stretches. Again, use your ears. Your face is tired, and you'll need to concentrate on keeping the tone focused.
Every other practice session add another 5-10 minutes to the "Focused Playing", while using the long tones to cool down.
In order to get better your going to have to wear out a whooole lotta reeds.