Being proactive.
AntoniaJames touched on this. When I buy produce, as soon as I get home, I deal with it. I put everything in sturdy, plastic zip-top bags (I reuse these over and over by turning them inside out and drying them after each use) with a paper towel in the bottom. I separate greens from vegetables (for instance, cutting off beet greens and separating them from the roots), wash and dry the greens, and roast root veggies ahead of time. Almost every week, I do a big batch of roasted veggies--beets, onions, carrots, parsnips, celery root, potatoes, etc. That way, I always have something healthy and already cooked ready for me.
When I buy produce at the farmer's market, I wash it immediately. It seems like a small step, but it can seem like a big one when you're hungry and impatient.
Mindfulness is also important. Sounds cheesy, but if you keep in mind that you're aiming for less waste in the kitchen, you tend to do just that. It takes a little effort on your part, but soon enough you fall into the habit of using everything. Also see: http://www.culinate.com/mix/dinner_guest/kitchen_thrift

I try to keep a well stocked pantry and freezer that allows me to work through just about any leftovers we might have. I also try to freeze portions of anything we made a lot of so we don't get tired of eating it and have an easy meal later on. Finally, I try working my way through the freezer completely every couple months allowing myself to only buy fresh vegetables or dairy to go with whatever I have in mind. I do end up going to the grocery store quite a bit more than I want to considering I don't want home through a lovely street market each evening (ahhhh, Paris!) but that tends to help too.

Chickens! They adore: mushy bananas; shriveled grapes; overripe melon; dried out rice/pasta/potatoes; gingerbread; the last piece of pie; stale cookies; leftover salad; and so on.

These are all perfect ideas. Great compilation of ways to end food waste. Composting has made a huge difference in that regard in our house AND with recycling, has cut our regular garbage to just a bag or two a week. Great for a family of 4!

I don't shop until I use what I have. This was my New Year's Resolution and its saving me money and helps me prevent waste.

I keep the vegetable ends to make stocks and soups, too. I also keep the parmesan rinds, too. Freeze them all. I do a lot of jamming and canning, too. Anything that looks a little sad, I try to turn it into a jam or pickle. Sometimes just an infusion- like infused vinegars, vodka, cherry jump, etc. All those vanilla bean shells, when you just use the seeds, I keep those. After I've accumulated about ten, I get a 750 ml container of cheap vodka and put the pods in there. Four weeks later its vanilla extract. I also have a compost bin. With egg shells, I save those in a separate compost container. When I've got a bucket full, I douse them in boiling water and whirl them in my food processor. I add some to the compost heap, and the rest of the slurry I feed to my tomato plants.
MTM- we give our dog vegetable scraps, too! He loves them. When I make tomato sauce, I save all the skins and freeze them in small plastic bags. The dog gets a plastic pack of tomato scraps about once a week. Yogurt that is nearing extinction becomes smoothie popsicle.

Prepare less. Freeze left overs and mark them on my calendar so I remember to use it.

I bring my lunch to work everyday. Sometimes it's leftovers from the night before, sometimes it's "garbage salad" with random odds and ends, sometimes it's kind of a smorgasbord. I do as others have said and try to "shop" in the freezer or pantry. And we have a dog. She gets an enhanced meal sometimes. I'm terrible with condiments and special ingredients though. I have a lot of jars and bottles that are full save for one or two tablespoons. Agree with no grocery shopping while hungry and prepping stuff as soon as you get it. I think the best way is to shop the way a lot of people outside the US do -- for fresh things to be used that day, nearly every day. Alas I usually can't figure out a way to work that method into my day and budget.

Cooking up as many of the veggies that I buy within 24 hours of bringing them home from the farmers' markets. Most cooked vegetables keep beautifully. Of course, as others have said, mapping out the week's meals, thinking about what needs to be used now and then using it, not keeping a whole lot of food in the fridge or freezer at a time, and re-purposing all leftovers are all key. But my number one is to cook my veggies ASAP. It makes meal prep gloriously easy, too, especially now that the weather's warming up, making room-temperature food is so appealing. ;o)

Eat more.

Me too! Plan ahead - bones and carcasses get saved for stock, along with appropriate veggie trimmings. Other veggies, eggshells and coffee go in the compost. Leftover grains and rice get made into salad for lunch the next day. Can the excess from the garden if you - ahem - obsessively over plant. And another trick I rely on heavily - share with the neighbors!!!

Never go shopping when you're hungry. I always buy too much whenever I'm hungry and all these thoughts of what I can make with this or that. Then later, I wonder what the heck I was thinking and the food goes to waste.

Agree with boulangere. Also as much as possible goes into composting for my garden. Also freeze, dehydrate and can.

Like boulangere, for me it has been about learning to make "just enough" - too many leftovers were my biggest waste. The second biggest: taking all the little scraps of veg (stems, leafy greens, etc) and freeze them, using them later to make stock or as a sort of "bouquet garni" in roasted or simmered dishes.

What's been working well for me is to at least sketch out a week's menu on Sunday morning, not to overbuy in the first place, and consistently factor in repurposing or freezing leftovers.