RAS strafing explained in one minute
Notice how in the example clip the guy misses almost all shots on me while I'm doing the ras strafe, compared to when I am on the ground strafing normally.
Recap:
(This is for right to left)
Forward pattern - D + scroll down + scroll up + W + A + S
Backwards pattern - D + scroll down + scroll up + S + A
Note: I have scroll down binded to jump and scroll up bounded to W