Haynes manual listing the basics would definitely be a good start Tim. You unscrew the spark plugs and look at the electrode/prong and if it's just a nice brown its good condition, if it is a mess of any kind, it's past time to replace. Spark plug wires should be checked with a multimeter to have contant resistance in them across the board to spec of what the wires should be. You can also visually look for little cracks or something and sometimes even running the car in the dark with the hood open will tell you something if you can see arcing from the wires. Both these things should be changed at intervals. Spark plugs depending on the type and how you drive your car and what is all done to it can last anywhere from 5000 kms, to over 100K. Wires usually last a while longer. Actually I have a 1978 Toyota celica with original wires in it which are still good.
