Save up all of your vegetable scraps, and then use them to make a yummy veggie stock! I attached a website that breaks it down pretty nicely, since it is a little more complex than just throw it in a pot and go crazy, BUT, for me personally, I pretty much just throw it all in a pot and go crazy, and it has only failed me once. I avoid saving peppers, broccoli, cucumber, cauliflower, potato skins, and tend to go light on leafy greens as all of these will add either a weird flavour or weird texture to the end stock.
Reduce, reuse, recycle!