There's really no need to practice at all on anything but the real thing --- you'll figure it out before you're done with the quarter you got. There's not a lot to it. Just take a little air with the smoke as you inhale. If you start to feel like you are going to cough, stop pulling smoke and suck in some air to bring what smoke you have inhaled down into your lungs. Hold for a few seconds, then blow it out. Repeat as necessary.