One thing that I found that works in some classes is letting the student get in front of the class to demonstrate a concept. When they are successful, the other students as well as myself let the person know they did a great job. When I am teaching, I tend to credit the students for their answers. Another method I use is extra credit. The students will do just about anything for an extra point.
Food also works.
I also want the students to have interactions while trying to work. As you look at pictures of my classroom, you will see that the students are thrilled to help a friend. This involves the students in working together to create a positive learning environment.