Extractor, yoke, firing pin, cylinder (where it contacts yoke).
Any more then that you're over doing it. Pretty much any part you believe will make contact with another metal part.
You DONT want oil in the berrel (first shot it will be gone anwyays but still), or in the cylinders...
(that's how I've done it anyways. Then again I've seen guns drenched in oil shoot ok)
oil is mainly so that metal on metal doesnt occur, and provide that extra glide between 2 parts... so just look at your gun... see how it works, and where it should need oil... one drop is probably more then good enough... then just wipe most of it down before shooting.
If you're shooting and you get a puff of oil... then yeah you over did it.
Luke