Half Guard Sweep
Here is a half guard sweep that I use a lot. In the video I'll show the move, then break it down, then show it one more time. Helping me out is LockFlows own Kevinlace.
Keep a hold of the knee
Left knee to the belt
Back to side control
Starting out in half guard
Make sure your knee is on the outside of your opponents body.
Your left arm should be under your opponents right armpit. Your right hand on his left knee (grabbing the gi). You also need to be turned on your side.
While on your side, you're going to lift your left leg up (hooking your opponents right leg) and pulling your opponents left knee inward.
Maintain control though the whole sweep.
Keep a hold of the knee so your opponent can't turn back in towards you.
Now bring your left knee over and place it right next to your opponents belt.
Once your knee is next to your opponents belt you can let go of the knee, swim your left arm under his right arm and move into side control.
From here you can use the "side control to arm triangle" move that I showed earlier.