Finding a good container is the first step to Garrauxing(unless you plan on growing in the ground). The best practice here from a sustainability standpoint is to use recycle something that is generally garbage. Old milk jugs and gatorade bottles are good examples of containers, but to get a better yield, a larger container would be ideal. Larger containers could include old cracked plastic tubs and forklift pallets. Of course, you could just buy a pot. However, whatever container you choose. make sure it has proper drainage (plants can drown too)
Soil can be obtained either buy purchasing it (soil is dirt cheap) or by finding it local. its best to ensure that the soil you choose is rich enough to grow your desired vegetation. If you plan on eating what you grow (like some of the plants I have under the project tab) then I would suggest using soil that has little to no fertilizer for it will bioaccumulate into your body.
Seeds can be purchased at local convenience stores or harvested from plants or fruits of the desired vegetation. My favorite place to purchase seeds is from the Baker Creek Heirloom Seed catalog which has over 1500 types of rare non-genetically modified seeds. you can also start a plant by buying seedlings or taking stem cuttings of the plant (stem cutting practices will not be covered on this site, but worth researching!).
Water, especially in America, is very easily accessible. However, water shortages in the near future will be expected from our ever consuming society. Sooo, if you can, set up rain catchers to collect water and not only preserve our reservoirs and save money on the water bills. If tap water is used, it is always good practice to distil the water over night (that is to let it sit) and that helps settle alot of the metal/chemical particles that are not particularly healthy for our green buddies