There are several ways to do it. However you do it, you need good mouse control (If you've played a lot of first-person shooter games this should be easy, if you haven't it might take a while to get). If you can't jump-shot, ask how to strafe-kite. I can't do it all that well, but some other people can. Okay, so for the 3 methods of jump-shot...
1) (What I use), click and hold both LMB and RMB, this will allow you to run and control where you are running. When you jump, move the mouse until you turn at least 90 degrees (so the target is in the 180 degree radius in front of you) and use an instant shot. Then either finish the spin, or spin back.
2) Auto-run or run with the W button, and only hold the RMB when you are turning/jumping. Then jump, hold RMB, and turn like mentioned above.
3) (Quicker Jump-shot, less control variant) Have auto-run on and hold LMB to look behind you. Keep holding LMB while you hit jump + RMB and you will instantly turn around, allowing you to fire and spin back to run forward again.
It should also be noted that it's best to have the shots you use while jump-shotting on an action bar you can use a hotkey for. Since your mouse is used to move, you need to use the keyboard to shoot. If, while running with the mouse-run method, you need to change aspects, lay a trap, etc, and said aspect/trap is NOT on an action bar you can use a hotkey on, then turn on auto-run or hold W while you press the button with your mouse.
I hope that covers it.