Kalista microing?

The trick I feel, is to be able to attack targets and move at the same time, and not just moving, but moving in the correct direction, but the thing is when I attack I'll either not move at all, or move forward instead of back, or to the side. I've seen good kalistas just attack-move in any direction they need to, and kite perfectly, which means you can never get them.

I need to learn how to do that, but I just cant seem to attack in one direction and move in the other at the same time -_-;

If I'm attacking a minion or a champ, that means I'm not moving off to the side, or to the back...so.... >.<;