On rare occasions, you may have a good go at making your own starter only to find that it smells or tastes horrid or that the bread or other baked goods it produces are not very pleasant. This means that the bacteria that has occupied your starter is not the right kind, and the lactic acid, which makes the starter inhospitable to other organisms, hasn’t got going. You will need to discard this one and start over, moving your culture to a different room.
I most often find that people who are having difficulties have meddled with the process of trying to fast-track it or are not refreshing frequently enough. Please be patient. You do not need hot water, live yeast, grapes or any other extra thing to get wild yeast going. It is naturally present in the grain you use and, for the best results, use stone ground, organic, wholemeal flour.
For people who are completely new to sourdough, I suggest using an established culture as it is easier to get started with. When people first get going and they are keen to bake bread straight away, it is faster and simpler to use an established one that already contains active yeasts that have been populating the dough over a long period of time. An established dough is stable, active, and resilient. It is because of its established bacteria and yeast that in the first attempts of making sourdough bread you will be guaranteed a more pleasantly flavoured sourdough and more likely to continue baking. Try asking your local sourdough bakery if they are happy to give you some of theirs.