Give the robber what he wants--money or personal items--without hesitation. Your life is worth more than your cash and jewelry.
Talk only if you're spoken to. Avoid getting angry and never speak sarcastically. Words are weapons that can offend and incite. Keep yours in their holster.
If the mugger asks for your money or jewelry, gently toss the items away from you. This may shift his focus. If he walks over to retrieve them, you may have a chance to run.
Grab your keys. It the mugger physically attack you, you can use the keys to jab at his eyes. Just the keys out from between your fingers and punch.
Stay calm. You won't be able to weigh your options--to run or fight, to remain silent or start screaming--unless you have a clear head. If you do run, you want to be calm enough to pick your route away from the mugger and dash towards a populated, well-lit area.