Agree with all of the above, but sometimes we bounce up and down lightly with my little one and she burps just from the up and down motion. So you might want to try that if nothing else works n

I'm with @melodyly ! I do that I rub his back starting from the bottom going up, like a little back massage and he starts wiggling around and out comes the burp! :)

Start from lower back and slowly work your way up and start again low. Works for my son.

Try the sitting position