Situational awareness is the key. Muggers, etc., have a script in their head of how they think the encounter is going to play out, and it usually involves either ambushing or rushing, closing the reactionary gap, and getting in close to their victim as quickly as possible. If you are aware of how criminals operate and watch for the early warning signs, you can break their narrative. That puts them on the back foot and they go away. I've only ever had to square up and put my hand on the grip here twice, as soon as it became clear they were maneuvering on me. In both cases they immediately seemed to suddenly remember important criminal business elsewhere and departed.