Here's something to start with.
One of the first things you should do is to open the hood and run the engine in the dark. If there's a stray spark it will show. A bad plug wire or a carbon track on the cap can do this and make a ticking noise. Fix that before going any further.
Take off the cap and look carefully at its inside surface. It should be shiny and smooth. Any cracks or carbon tracks = a bad cap. Look at the posts inside the cap, and at the tip of the rotor. Normally, the rotor should come very close to the posts, but not touch them, and the surface of each post will look pitted and a little scorched after a while. So will the part of the rotor that passes by the posts. If you see a shiny spot on one post or the outside edge of the rotor, you can suspect that it is hitting.
If you grasp the distributor shaft, it should not be possible to wiggle it sideways at all. A little up-down play is all right, but if it goes sideways it's worn.
You should also check the little carbon button in the center of the cap (inside) to see if it's still there. It should contact the spring on top of the rotor. If it is broken or lost, the car might still run, but the spring tip might be clicking against the cap as it turns.