First, I would suggest reading through these forums before posting. We already have a thread on this exact subject. I'm just going to paste what user TomatoTom posted in response:

"Technically it goes down to practice and not getting stuck on anything as best as possible. The basic techniques is strafe running. Strafing makes u move faster at all times so its best to hold it throughout the run. If u using keyboard. Its WA, WD, SA, SD. If u using controller, point ur stick at the four corners like a square."