One thing I have found helpful in determining if my starter is ready to use, in addition to the visual and procedural clues, is to smell it. With my starter (100% hydration), I take it out of the refrigerator and allow it to come to room temperature. Then I discard all but about 60-75 grams (depending on what I'll need). Then I feed it (1-1-1). As it feeds, it has an alcohol type smell. As it gets just past doubling, crowns, and just starts to recede, the odor changes to a more healthy, somewhat sweeter, fresh bread smell. This is the point I use what I need for pizza (or bread), feed the extra and put it back in the refrigerator.
When I am not using it...just feeding it...I take it out of the fridge and let it come to room temperature, stir it, measure out about 60-75 grams and feed it 1-1-1. Then it goes back in the refrigerator.
So far this has worked well, as I am getting very good taste in my breads and pizzas. I do still include a pinch of IDY in my recipes as it gives me a little oomph that starter alone doesn't. I'm hoping (wondering if), as my starter matures (it is less than a year old) it will only get better and stronger.