I need 4 holes on the wall for a bracket mounting, the 1st hole can be anywhere, but the 3 other holes need to follow the 1st hole and need to be extremely accurate or the screw will not fit, from my experience its difficult for me to drill the hole so accurate, can have only +- 1mm variance for mistake only for each hole.

How to make such accurate drilling ? drawing circle on the wall is easy, but once drilling starts, the drill bit will some how "move" a bit if certain part of the wall is harder, how to prevent the bit from "moving" ?