Not to knock on techinspectors post, but he left out one important thing...

Make these adjustments VERY SLOWLY! You have to give the tappet time to "adjust" to your adjustments.

Also, when you are done, shut the engine off and let it rest for a minute or three. Then restart it to see if and tappets "adjusted" themselves again and need more attention.

Also, to make the job less messy (cleaner is always better), there are oil deflectors that clip to the rockers that keep the oil from getting everwhere. The last set I saw was at Pep Boys.