I avoid bribes and incentives as much as possible, but when it comes to a sub, I'm all about giving that person an extra dose of leverage so they can get the best out of my kids. I know the quality of instruction is not nearly what it could be without me there, but if my kids can step up to the plate, they'll get more out of the day than otherwise. The guest teacher can then do more teaching than managing.
The guest teacher passes out tickets galore to students who are doing what they're asked to do. The child writes their name on the ticket and places it inside the can. The same kiddo can even get several tickets throughout the day. In fact, I hope they do. At the end of the day, the guest teacher takes out a pre-determined number of tickets, and those kids win a prize of some sort but never nothing fancy. It really does give the guest teacher the advantage.
(Disclaimer: Many kids end up being recognized throughout the day, but I don't like that only a few ultimately walk away with something. This is why I only do this when I'm gone, and when I'm gone, I'm desperate. Good thing that's not very often.)