A basic form of self-inquiry is to look at (i) what comes and goes and (ii) what doesn't.
Notice sounds, and how they come and go. Notice smells and tastes, and how they come and go. Notice sensations, and how they come and go. Notice thoughts, and how they come and go. Take time to notice each of these.
Notice if there is anything that does not come and go. Notice the space it all comes and goes within. Notice the awareness it all comes and goes within. Notice awareness aware of itself.
If "I" am any of these, what is it? Am I the content that comes and goes, living its own life? Or do I seem to be that which does not come and go, the space and awareness it unfolds within?
Move the arm up and down a few times. Can you find any doer of that action? Can you find any chooser? Does it seem to happen on its own?
Notice the tendency to jump to a memory, a thought, an expectation, to find the "right" answer. Is this too part of the content? Is this too something that comes and goes? Is this too something that lives its own life?
Notice again that which does not come and go. Notice the space and awareness any content comes and goes within. Can you find any limits? Can you find a beginning? An end? Does it have any color? How does it relate to its content? Is it touched by any content? Can it be harmed by any content? Does it resist any content? Is it separate from its content? Is there a separation anywhere? Is there an I in the content? Is there an I in the seeing?
Who or what are you?
I see that a trick here is to not be too heavy handed. To leave the questions as a gentle invitation for seeing it for oneself. To stay with, and allow the pointers to come from, immeditate experience. The pointers above can certainly be refined to (a) allow more space for people to find their own answers and (b) come more directly from immediate experience.