The easiest way to do this is in Serenity Waste. You will come across some low level Kraggons and Kraggon Pebbles (level 2-4). If you do not have the sniper rifle yet, you can come back later, when you are higher level, it will be even easier. When you jump, the Kraggons will run right below you. As the game does not register if you are aiming forward, you can just jump, aim right below you (there will be two-three Kraggons waiting for you to land), spin 360 and shoot. If you are high enough level, it is one hit kill, even if the Kraggons have full health. To make it even easier, air boost after jumping, so you have more time to align your shot.