Wallstrafing
Wallstrafing is a trick which lets you move at higher walking speed by strafing against the wall. When wallstrafing, you are accelerating as you would do without a wall, but then your speed gets cut a little bit to stay parallel to the wall.
How-to
Simply walk forward and hold your strafe button while rubbing against the wall.
Wallstrafing seems to give the best speed while facing the wall 8 degrees. You can see your angle by using a command cl_showpos (for Source).
Wallstrafe Jumping
Wallstrafejumping is another trick which uses wallstrafing as a main speed gaining method. Bunnyhopping while rubbing against a wall at a certain angle lets you gain speed easier than the normal bunnyhoping, and it turns out to be faster due to eliminating the main phase of slow speed gain in the normal bunnyhopping - switching the view moving direction and the strafe button. Viewangle must be decreased together while speed is increasing, exactly like you move the view slower as you gain more speed while bunnyhopping.