Easier way: Get all your motor mount bolts finger tight (not GI Joe Kung Fu grip tight). You should be able to move the motor back and forth, but it should require some force.
For reference, roll your car along the floor. Note how far it rolls, and how loud the mesh is. Keep moving your motor around until the car rolls the easiest, and the mesh is the the most quiet.
Once you have it where you like it, hold the engine firmly in place and tighten the bolts. Check the mesh again by rolling the car before you snug everything fully as the mesh may change as you tighten.