What do you want to do sadhana for? The aim should not be the satisfaction of egoism: "I want to be a great yogi; I shall have so much power and with that power I shall establish myself in the world." All such thoughts must be thrown far away.
You want accuracy, but not representation. If you know how to make the figuration, it doesn't work. Anything you can make, you make by accident. In painting, you have to know what you do, not how, when you do it.