Is there a trick in marking a surface where to drill holes.
Like the enclosed picture of a door knocker. Do you coat it with lipstick
And press it against the door, so the drill holes line up for the screws
In the right position coming from the other-side of the door?

That's one way... I'd put masking tape on the door first... makes it easier to see.

With a metal door, use a center punch to make a small indent. After drilling, visually center the drill but most drill today have a level on them. Both of mine do.

Oh that good. It would leave an impression

When you do it... circle one of the holes... then use a level to make sure the second is exactly where it needs to be and make any correction needed before you drill. (with the door closed)

Hard to see if its off kilter standing that close.

Okay that system would be applicable in similar applications.

okay that system would be applicable in similar applications.

Yes it would... one of those little shortcuts you learn along the way.