Pilot holes: Pre-drill with a bit slightly smaller than your screw. Countersink screws: For a flush finish. Avoid edges (at least 1" from board ends).

Use a hole saw kit (standard size: 2⅛ inches for knob, 1-inch crossbore for latch).

Drill a hole at eye level, insert the peephole from the outside, and screw the interior lens into place.