Thanks to qwkcpe for the pics involving the red car.
If you need a refresher on what caster, camber, and toe are, see here: http://www.ozebiz.com.au/racetech/theory/align.html
On to the measurement. First, the caster. In my opinion, this setting is less critical than the rest, and since it's also considerably harder to measure, and often unadjustable, I usually recommend setting it as far positive (strut tops to the rear) as possible, within reason. If the car drifts to one side after all is said and done, remove caster from the side it’s pulling toward. Norm Petersen says "You can make a simple jig from strips of wood or metal to make steering to a specific angle easier and more accurate. I made one for 14.5 degrees (left and right) when I upgraded the homemade camber measurement apparatus to one with a pivot, two magnetic levels, and a dial indicator for easier reading and less math. For 14.5 degrees, caster = 2.0 x (camber difference)." In other words measure the camber with the wheels turned 14.5 degrees left, then 14.5 degrees right, and multiply the difference in measurements by 2 and that's your caster. I drive a fox body and I just set it all the way back. One of these days I'll measure it.
Next, the camber. Easy. You just want to measure how far out of vertical the wheels are. With the car parked on a level floor and with the wheels pointed so they’re straight ahead (regardless of steering wheel position, you can fix that later, just go where you know the car tracks straight ahead), place a construction level against the bottom lip of one front wheel. Hold it so the level indicates perfect vertical, then using a ruler or tape measure, measure the distance from the edge of the level to the top edge of the wheel. See the end for how to convert this measurement into camber degrees.
Note: If you can't get a level solidly against the wheel, here are two options:
1) Cut a length of straight 1x4 or 2x4 wood exactly the diameter of the lip of your wheel to use as a standoff for your level
2) as seen in the camber pic on the green car, get some 3/16-inch diameter “all-thread” at the hardware store (rod that's completely threaded, end to end) and cut a couple of 4-inch lengths of it. Drill holes in the frame of your level or in your standoff so that they match up with the diameter of the lip of your wheels, and tap them for the all-thread. Insert the all-thread in the holes to make leveling screws, and holding the level up to your wheel, adjust the screws so the level is perfectly perpendicular. Using a ruler or calipers, measuere the length of each screw. Subtract the shorter one from the longer one, and the result is your distance out-of-vertical. Use the chart at the end to convert to camber degrees.
Using leveling screws:
Now, onto the Toe setting, always done last because camber can have such a dramatic effect on it: You're measuring how far the wheels are toe-'d out or toe'd in, which means you want to compare the distance between the fronts of the wheels and the distance between the rears of the same wheels. Specifically between reference points halfway up the front of the wheels and halfway up the backs of the wheels. You usually can’t just measure across between these points because the car gets in the way, so you need a “caliper” of some sort to transfer these points down to the ground level for measurement. This is easy to make out of a nice straight 8-foot length of 1x2 lumber and a couple of shelf brackets. Or, a shelf bracket and a square.
I set the rail under the car so it runs side to side, align the locked bracket with a specific portion of the wheel (or, alternatively, the tire tread) halfway up the back of the tire, then position the other end of the rail to take a measurement. Before I measure, I go back and make sure the fixed end of the rail is still in position because it’s easy to move as you position the other end.
Then I place the slider bracket on the other end and match it up against the same part of the wheel or tire as the bracket on the other side of the car. Make note of the measurement.
Now bring the rail to the front of the tires and make another measurement the same way. The difference between the two distances, front and rear, is toe. I pre-marked the rail in 1/16th increments where the slider would go but in any case that’s how you do it. If you use this bracket device you’ll have to be precise about how the “slider” bracket sits on the rail to maintain accuracy.
Adjusting the toe is easy, at least on a Mustang. You probably don’t even need to raise the car. By holding the outer tie rod end with some vice grips or channel-locks, take a 7/8 wrench and loosen the jamnut. Then use pliers or a 14mm wrench on the tie rod itself to turn it inward or outward, then hold the assembly still while you tighten the jamnut. A little goes a long way, and if the wheel was crooked now’s your chance to fix it. One full turn of a tie rod should be 1/16th inch of toe change. If you need to toe the wheels in from where they are, start with the wheel opposite where the steering wheel is pointing. In other words if the wheel points to the left, take toe out of the right wheel. If you don’t need to make a toe adjustment but you do need to straighten the wheel, add a little toe to the wheel on the side it points to and take the exact same amount out of the other side until the steering wheel runs straight.
Here's a chart for converting inches of camber into degrees of camber, depending on the size of your wheels.
Here are some other threads and links for reference:
Alignment tools for those who want to buy instead of make: