On one website a man recommended pulling out your wallet, and then tossing it down to the ground in front of the mugger.   As the mugger then crouches down and also looks down at the wallet to pick it up, then you pull your gun, when his eyes are off you and he is also out of position to attack.

Although, really, is the stuff inside your wallet really worth killing another human being over??   Certainly a person's life is worth much more than that.  Best thing for you to do would be to throw the wallet down and then run away.   The mugger would then have no reason at all to chase you.

Just run as fast as you can, while you dial 911 on your phone.