I'm not a pro and have made tons of crappy loaves, but the easiest for me has been King Arthur baking's website, from making a starter to using the discard in recipes I use their rustic loaf and the extra tangy recipes. The Sourdough School has a great book by Vanessa Kimbell on the mechanics of it all, so it all kind of clicked when I was actually doing the bread making. I think just powering through the sad loaves and learning every time is key...and DON'T rush it, it's going to take all day 🤷‍♀️. Hopefully this helps!