I've adjusted my valves 4 or 5 times now. I've done it the traditional way which I thought was the most difficult as getting the feeler in is not super easy. I've done it the back side method which was a little easier. In both cases, I find that it is easier to maneuver around if you remove the side engine tin.
The last few times was with the Kirk Valve Lash adjusting tool - this (by far) gave me the best feeling for accuracy and I highly recommend this (or similar) tool. By far, the best $85 I've ever spent on a tool.
Porsche 911 (1974-1989) - Tools - Page 7
Lastly, my most recent valve adjust was with the engine out and on a stand - wow, does that make it easy
