Starting a compost pile is always a good way to help provide nutrients organically. You could separate your food and throw the vegetables, egg shells, fruit peels, stuff of that nature. Some people use meats, I personally would not, they attract the wrong kinds of bugs. A compost pile takes some time to get enough to use on a large scale garden though.
Otherwise, you could look into Subcool's Super Soil recipe and use that. Actually, if you had to start something right now, I would recommend the Super Soil. It will take about a month to "cook" the soil outdoors in the sun, but It could be ready by may and you could just grow plants in pots in base soil until your Super Soil was ready and then put them in the ground.