I hate wasting food too! I try to only buy what I am going to use within a year (for canned stuff).

On things that don't have an expiration date, take a piece of masking tape and put the date you bought it on there. I even do this with spices as some don't come with a date on it.

It's my refrig that gets me. I will buy food and forget I bought it and it goes bad. It makes me so mad when I do that. Just recently we had to throw away a cantaloupe that had gone bad and the price was so good on it (buy 1 get 1 free). We ate the one but I forgot about the other one.