I just changed my glow plugs on '85 300CD. Go to diesel forum and look for that thread. Job was tedious because of location of plugs but not complex. You will definately need to remove the fuel lines, do that first and put them (good Larry Bible suggestion) in a plastic bag to keep very clean.
There is a little (8mm) nut that holds the wire to the plug that is easy to drop and the replacement plugs (available from FastLand overnight) do not have additional nuts! Put a cloth under the plug to catch the nuts that you will drop for sure. Use 10 W 40 to lubricate them before starting and you can use fingers (barely) to do most of removal work.
Just be patient and give yourself enough time to do the job.