Living in a one person household my main reason for food-waste is things going bad before I can finish them. I don't mean past the expiration date I mean them growing mold. This doesn't just apply to things forgotten in the back of the fridge but also to things I eat regularly. This could to some extent be solved with preservatives but enough people avoid that for food producers to follow along. They proudly declare being preservative free which for me means that my pesto starts growing mold when the jar still half full even when stored in the fridge.
This is annoying since buying larger packages are often cheaper but not if you can't use them. Not to mention that some things are just hard to buy a small amount of. Last time I made soup I bought a thing of broccoli and celery but only used about half of it.
To solve this I have turned to freezing as much of my food as I can. After using as much of a produce as I need I cut up the rest put then in containers and freeze them. With a freshly defrosted freezer there are lots of room for them. This also allows me to later take out only a little bit depending on what I'm making I can put in the whole container or just a few pieces. This also makes future cooking faster since I don't need to cut it up then.
And so far I have found that there are very few foodstuffs that can't be frozen. Here are a few and my experience of using them.
Carbs
Bread and cake: (I bake my own and usually make two loaves at a time one goes in the fridge for eating and one in the freezer for later).
pasta and rice: works well but shouldn't be kept too long.
Potatoes: this is one of the things that doesn't freeze well.
Herbs, vegetables or fruits
All these has worked fine. They do unfortunately loose some of their structure and crunch so while they are excellent in stews, stir-fry, pie or anything that's heated I would't use them for a salad.
Meat or dairy
Meat: works fine though we are talking storing it for months rather than years.
Milk: takes a long time to thaw but that's all just remember to take it out a day or two before you need it and let it thaw in the fridge.
Cheese: works well. When it becomes difficult to cut for sandwiches I usually freeze it and save it to be grated the next time I need it.
Yogurt and similar: doesn't work it loose all structure becoming grainy.
These are some things I could think of on the top of my head but for anything specific you can always just google it.
This is annoying since buying larger packages are often cheaper but not if you can't use them. Not to mention that some things are just hard to buy a small amount of. Last time I made soup I bought a thing of broccoli and celery but only used about half of it. 
