The trick to walking through walls is to be in a different state of consciousness, this state or density of conscious form knows that matter is non existent and is easily attainable even from reductive sciences which state that all matter is 99% empty space, the matter itself, progressing a little further is actually nothing more than frequency harmonics of ether matter flux. Knowing this of course isn't the whole story, cause every sleep walker bumping into a wall would simply walk through it because their consciousness is currently off planet in some astral plane where this is normalized behavior. The second trick is to integrate this knowledge into living the 3d projection that makes up our reality, which means overwriting the belief system that matter is matter. One additional trick, is either to tackle walls in the astral form over and over to drill it into your comprehension, and or enter the astral in a wakened beta state but with a guide like anubis who has a tendency to walk people through walls with him. I have a friend in aus who has experienced this with him. And there are others online speaking to it. I also have known two personally that regularly used to see through walls, they never took the next step though.