For the first while, money will still hold a lot of value. There will be a lot of people that have faith that their little cotton tickets still mean something.
I really don't suggest just racking up debt while speculating that the economy is going to collapse and make your debt all better. That's about the same as going "Well, I -can- just file for bankruptcy..."
If you're that worried about collapse there is plenty you can do to be prepared for it. Learn to grow your own food for one. There are at least some plants you can grow inside your house, so it doesn't matter if you have no property to grow them on. There is also a technique called espalier, where you train trees and shrubs to grow flat against a wall or fence. These plants still produce fruit.
Growing an Espalier fruit tree
You should have several months to a years supply of spare food with a little excess. This is good practice in general, but imperative if your money is going to be worth less than the dirt you stand on.
Dried foods tend to last half a year, canned forever, frozen food for "a very long time" but we all hate freezerburn. This website has all the information you need, either directly or through links about freezing, canning, growing, pickling and drying food. Invaluable knowledge for surviving tough times.
Fruits and Vegetables
Now, finally... There are many, many people who are hoarding the coins that still have valuable metal in them. Old copper pennies are the poor mans gold reserve, nickels that are either made of nickel or coprenickle*, or even the old gold and silver coins. Some of these people are just waiting for a lift in the penny melting ban, while others speculate on a collapse and believe there will be value in non-fiat money when it happens.
Wise man once said, "If you don't hold it, you don't own it." and that will be true in the case of an economic collapse.
Survival is the easy part, and there's always room for a barter system for nice things like blankets and toilet paper. What I'd be most worried about is looters, abusers, and military invasion. (Possibly even your own countries so they can 'redistribute your excess to those less fortunate'.) If your country is looking bad, and there's another country that looks fine, you might just be better off going there until 'things settle down'. Before a true collapse, so you don't find every flight locked out and every ship that's gonna sail, gone.
That being said, you can always take an assessment of your skills and know what you would have to contribute to other peoples well being during that kind of crisis. If you can entertain, make wine, case bullets, teach children, cook hotdogs from tinfoil, coathangers and pop bottles... You are in a good position to sell yourself on the street. Er..
For the most part this is just an everyman strategy that's highly suitable for people who only have maybe a few thousand, tens or thousands, or maybe even hundreds of thousands... But it's all tied up in their home banks or stuffed in their mattresses and at complete risk of being useless.
Bonus idea: Sell your economically worthless money to foreigners for the historic value!
*Copper nickel alloy. I may be off on the name and or the spelling.
