When I got my first handgun, I had the same issue. Having no idea what lightly lubricate means. Then it was explained like this. Actually, part of it has been mentioned already:
If you think you are using too much, you likely are.
The second part to that is this:
If you think you're not using enough, you're likely using enough.
Oh, and a lot the time it really depends on the gun. 1911's tend to like more oil than most Striker fired guns. Glocks on the other hand, well, over lubrcating can actually cause malfunctions. You need very little oil on a Glock.