The Trick?......good eyes
usually. Get an RPM camber gague and always set your camber on a very flat surface. For the most accurate measurement, you should always have some empty rims lying around. When the tire is off the rim, it is very easy to make accurate adjustments because you're measuring the angle of the rim and not the balloon of the tire. For toe in, thats purely an eyeball measurement. However it is always easiest to measure toe in and make it equal when the car is on so that the servo is centered. Also, look at the toe from behind the car.