Disconnect the coil wire first for safety, making sure the motor won't accidentally start. Some guys prefer to remove all the plugs too, so that the engine is easier to rotate during the procedure. Make sure to mark your plug wires before disconecting, so you don't mix up the firing order when reinstalling them.
Next rotate the engine until the number one (#1) cylinder is on TDC just after the compression stroke (you can feel the compressed air by putting your finger over the spark plug hole).
Now you can adjust the following valves:
#1 intake - #1 exhaust - #2 intake - #3 exhaust - #4 intake - #5 exhaust
Next, rotate the engine until the number six (#6) cylinder is on TDC just after its compression stroke (one full revolution of the crank shaft). Now adjust the remainder of the valves:
#2 exhaust - #3 intake - #4 exhaust - #5 intake - #6 intake - #6 exhaust
Adjust the valves by backing off the adjuster so that the pushrod can be easily rotated between your thumb and forefinger. Then slowly tighten the adjuster until you can no longer rotate the pushrod. Tighten the adjuster an additional ¼ turn, for the proper preload on the hydraulic lifter.
Note: The valve adjustments should be done on an engine that has been warmed up. Make sure to let it cool off sufficiently so that you don't burn your fingers while rotating the pushrods. It is also a good idea to place a drop cloth or oil pan under the car/engine to prevent oil drips on the floor.