I've been asked this question by a number of people after they've read one or more of my articles warning of economic difficulties ahead. It's hard to answer them, because I've never been through an economic collapse as such - only severe economic difficulties. Even when visiting African nations whose economies had collapsed, I went there with hard currency that enabled me to buy what I needed, and I could always leave and head back to the 'bright lights' of a more stable nation.
However, Ferfal (his chosen nom de blog) experienced the collapse of Argentina's economy some years ago. In this video podcast, he describes what it was like and mentions things from which we can learn to prepare for what may lie ahead for us.
You'll find much more material on the subject at his blog. Recommended reading.