Man, I've read a bunch of Krishnamurti over the years, and the thing that always strikes me is how he demolishes the idea of practicing mindfulness as a technique. Like, he'd say paying attention to your breath or trying to observe thoughts is just another form of becoming a better controller, a better 'me'. He's ruthless about that. His whole deal is that awareness is something that happens when you stop trying to achieve it, when you see the futility of effort directed by the self.
Reading him feels like having someone constantly pulling the rug out from under you. You think you've grasped a concept about non-judgment, and then he points out that the very desire to be non-judgmental is a subtle form of judgment. It's frustrating and liberating at the same time. He doesn't give you a path; he insists the path is the problem. For self-awareness, he'd argue that the 'self' that is aware of itself is still thought, still memory, still the past observing itself. Real observation, to him, is without the observer—that split-second of pure seeing before thought names it.
I find his books, especially something like 'Freedom from the Known', useful not as instructions but as mirrors. They don't tell you how to be mindful; they expose all the ways you're not, and all the hidden motives behind why you want to be. It's less about adding a skill and more about shedding an entire approach to life.