I noticed that one of my clients would constantly "get ahead of himself" when attempting productions. He would blurt out several sounds at once, hoping one of them would be right. What he really needed to do was slow down and wait for my modeling.
So next session I turned to the penny system. I used a strip of paper with Sonic the Hedgehog characters on it. For each correct production a penny was added to the strip. We didn't move on to another word until he earned all 5 pennies. Simple.
The penny system slowed my client down significantly. He was more thoughtful with his productions and motivated to earn all 5 pennies. At the very end of the session I told him that I wanted to hear 2 more good productions and he responded with "no, we need 5!"
The penny system works great for clients who need to slow down their production or could a little extra motivation!