Making starter: Mix 1:1 water and flour, some[1] salt, leave in warmth for a while. Two or three days should be enough to start seeing bubbles. During the first week you should be taking away half of the starter, disposing of it (can try baking already, results will vary day by day), and refilling the starter with fresh flour, water and salt. Maintain constant ratios. This is to ensure your starter isn't dominated by wrong microbes. Using starter: Take some starter out every few days (you use it by mixing it with fresh flour, some water and leaving it for a few hours under cloth), and return what you took from the starter in flour and water (1:1 or experiment slightly). Happy sourdoughing! [1] - My proportions: glass (250 cm^3) of flour, glass of water, two or three tablespoons of salt. EDIT: Why salt? It's not something you need. Really, you can leave it out and get good sourdough. I opt for adding it because it makes the initial process shorter and a bit more forgiving. As time goes by, you can phase it out by simply not adding salt with water and flour after you take some for baking.
There are pros to more work-intensive recipes, ones where you refrigerate dough for 24 hours after forming with starter, knock back the bubbles etc. Richer flavour you get from doing it this way can definitely be a seller. Those same tricks with slow fermentation in the fridge also work for helping pizza dough obtain remarkable, complex taste. But, you can get a good bread just from mixing a gob of starter with flour, water, salt and more optional ingredients, and leave it in a damp cloth for 3-4 hours. I don't mind making or eating either, though only whipped out the fancy version when I really wanted something top shelf. In the end, it's all up to personal preference.