dig a 4 feet down by 4 feet wide and fill back in with better soil, where I'm at the soil is pretty acidic so I will be mixing in some wood ash and lime for ph buffering. The soil is also sandy and has a lot of clay so I also need to mix in some perlite and vermiculite other than that I plan on using a mixture of topsoil, peat, and decomposed wood. I have not grown outside yet but what you use will depend on your soil composition and water requirements. other than that start a compost pile if you don't already have one. compost banana peels, vegetable scraps, apple cores, potato peels, vegetable matter only never meats or proteins, throw in some worms to speed things up and if your like me and you fish you wont have to buy worms anymore