There are two ways to handle starter. Leave it on the counter, or toss it in the fridge.
If you leave it on the counter, it needs to be fed every day. I’d only recommend this approach if you actually use it daily to bake with. It does consume a lot of flour, so there’s that.
The fridge approach is better for the very casual baker. You can feed it, let it sit for a few hours to start fermenting, then toss it in the fridge. Mine lasts in the fridge for up to a week. So, when I’m not on a baking kick, I only feed it once a week. I’ve kept this last batch going for about a decade now with this method.
To feed it, the best ratio of starter/flour/water is 1/3 of each. I recommend using all purpose, unbleached flour. Plain old tap water is fine, unless you live in a place like Flint, MI where the water can kill you 😉
You can keep it dryer or wetter, depending upon your baking approach. I tend to keep mine wetter, like very thick pancake batter. I tend to make more hydrated breads.
Also, you don’t need a ton of it if you aren’t baking. For instance, you can keep just a few tablespoons going with the fridge method, thereby reducing your flour consumption.
So, when you want to use your starter, it’s best to feed it the day before you use it. That’ll put it at its maximum peak for yeast. When I know I’m going to bake, I take the counter approach. I leave it on the counter (instead of the fridge) for a few days before I bake to bulk up the amount to be twice what I’ll actually use when baking. When you increase the size, it loses some of its sourness. So if you do it for a few days to bulk it up, it’ll be nice and sour once you do bake.
Then to use it, just follow any ol’ online recipe for something with sourdough in it. There are a billion recipes available 🙂
If your starter seems to be lack luster, not very sour, sort of flat, or other, you can perk it up.
This article, which is just a repost from an amazing book, uses fruit juice. I’ve heard raison juice is very affective too.
Alternatively, you can toss in a spoonfull of whole wheat or rye flour to give it some extra punch.