Honestly there is no specific technique. Even if you hit the same exact line everytime it just takes some feeling to do it but no techniques. Every single jump and bump is going to take a different approach and you'll just have to experiement with being on throttle, off throttle, slight throttle, or brakes. Just try to hit jumps as straight as you can... hit it when your turning or the buggy is carrying some sideways momentum and it will really screw you up in the air.