Dare I say that the answer will be different for different types of motor, and that the only way to correctly do this is to start with the motor connection diagram.
There are some easy ones, eg. a three phase motor is reversed by swapping any two leads, and some single phase motors are reversed by swapping connections on the start winding. Some motors cannot be reversed by a simple lead change.
The motor connection diagram is often found on the nameplate or in the terminal box.
-Jon
