Well apart from reducing usage of oil (oil is used to make agrochemicals to grow food and also to power food processing systems and is linked to biofuels which take farm-land away from use in food-production), you can also reduce meat consumption. The way that works is, it takes about five-six times as much grain to feed a person meat because the energy has to go through another animal first and of course the animal wastes a great deal though the inefficient digestion process and losses in heat and movement. Thus, people driving to a restaurant to dig into their stake reduces grain production and increases demand at the same time.
People don't realise that in the Western world, only about 10% of income is spent on food whereas in the less developed world, that figure is 70-80%.
Part of the reason we're facing this problem now, is that the growing wealth in China is enabling a 'Westernization' of their diet. They're eating more meat than they used to.
You can if you like, read all about it on various news websites. Thanks for expressing an interest!