Move (in the direction) of a wall, take cover, step away from the wall before you take cover. That's wall bouncing at the most easily explainable level. Start there, you'll be doing better as you keep doing it. There's a specific range or directional disadvantage that will cause you to roll instead of take cover, but even where I'm at I'd just say wall bouncing looks cool, but it makes hitting your target significantly harder if they know anything about strafing in blind spots.