I hate to spend money for organic berries and have them mold in the refrigerator before I can eat them.
I recently saw this little trick and tried it and it really does work:
When you get your berries home, prepare a mixture of one part vinegar (white or apple cider probably work best) and 10 parts water. Dump the berries into the mixture and swirl around. Drain, rinse if you want (though the mixture is so diluted I find you can't taste the vinegar) and pop in the fridge.
The vinegar kills any mold spores and other bacteria that might be on the surface of the fruit, and voila! Raspberries will last a week or more, and I've had strawberries go almost two weeks without getting moldy and soft.
Celery is another thing that I end up throwing out because it's limp before I use it all. If you wrap your celery in tin foil before placing it in the fridge it will last for weeks, and it will still be fresh and crisp when you pull it out. This also works for stored broccoli for seven weeks wrapped in tin foil, and heads of lettuce for at least six weeks.