I have a leaven that is about 17 years old. I think that the instructions in the article are a good start. However, it really is about feeding the yeast culture in the starter. The longer you have the leaven the more robust it becomes. I store mine in the refridgerator and bring it out in the morning I want to make bread. I add some flour and water to get to the consistency of thick cream and allow it to bubble up. I then take what I need for my bread and place the starter back in the refridgerator.
I add more flour (about half the quantity I intend for the final bread) and water and allow to bubble up. I make a dough by adding flour and salt and allow to rise (about 4 hours depending on temperature). I then tin the bread and place in the refridgerator overnight. In the morning, I remove the bread and allow to rise (2-4 hours??). Bake at 200C for about 50 mins.
I am sure that this seems rather vague. It was intentional because after baking bread (yeasted and sour dough) for 30 years I now do everything by look, feel and experience. That is not the way I work generally, but, with home-made bread I think it is essential. So, just keep baking and observing. You will eat a lot of mistakes, but, you will be rewarded immeasurably once you get the hang of it.