A points system is one of the most valuable classroom management tools and ESL teacher has. I split my class into teams based on the rows and get them to give me a team name based on a theme like fruits, animals etc. I use a tally system as it's easy to alter but you could do stars, smiley etc.
A points system has many benefits; Firstly, it's fun! Kids thrive on healthy competition. It can be as means to encourage students with extra points for longer answers or more participation. It's also a way to discipline students by taking away points for behavior you don't want.
Mostly, I think of it as way to communicate. It's a lot easier to point at a student who is standing up and erase their point than explain why they can't do that. Instant speedy discipline.
You can reward the best team with stickers, candies or just high fives.