One of the major purposes of of Legacy mode is so that "forward" is always whichever direction the camera is pointing, not which direction your character faces. Aiming is as simple as turning the camera. In legacy mode, left click and drag will turn the camera, as will right click and drag. The two have slightly different functionality when autorunning, but if you're not autorunning, they both just turn the camera.

In terms of a QE-WASD setup, the binds would look like this:
Move Forward : W
Move Back / Walk Backwards : S
Move Left / Turn Left : Q
Move Right / Turn Right : E
Strafe Left : Unbound
Strafe Right : Unbound
...
Move Camera to the Left : A
Move Camera to the Right : D

Then, despite the misleading naming of the keybinds, when you want to "turn", you move the camera with A/D and then move forward/backward with W/S. The Move/Turn binds will be for strafing.

(Tangential: the strafe keys should be mapped to Move Left / Move Right instead of Strafe Left / Strafe Right because the other major purpose of legacy mode is to be able to move at the same speed in all eight directions, instead of backpedaling. If you bind to Strafe instead of Move, you will backpedal if moving back and to the side simultanously. Binding to Move avoids this.)