Drill exactly
Marking the holes with pencil is often inaccurate. Especially when drilling on tiles you can z.T. bad control. But if, for example, a bar are mounted exactly vertically, pinpoint marking is valuable.
But if you have colored adhesive dots (from the paper business) at hand, so you can stick over the marked spot, then easily check the accuracy of fit and drill to the point exactly. When attaching my shower screen, this technique has proven very good.
