I've made natural leaven once before, but never got around to baking much bread and ended up throwing it away.
I'm trying to get a wild starter going again, but ended up killing it.
These are the steps I went through:
1. I mixed fresh ground wheat (hard and soft spring from wheatmontana) with bottled water 50/50.
2. Left it out at room temp (around 65F) for about 3 days
3. It started bubbling on the third day and I started feeding it with store bought all-purpose flour (only once a day).