Really. I have been doing this almost daily for about 5 years now.
Just sit in a alert posture, close your eyes, or softly gaze at something like a candle flame, or buddha image.
Relax your face, hands, maintain an alert pose.
Then pay attention to some aspect of your breathing function, the wind in your nose, or larynx, or the motion of your chest and belly. Let all the clamor and mental processes just go hither and yon. You cannot stop your thoughts, so don't stress yourself by trying; it won't work. When you notice you have lost the attention on your breath simply return to it.
The "depth" will gradually deepen with practice, but do not look for anything special to happen.
And sometimes something special does happen. When it does, just notice it and let it go. You can come back to it later.
it is that simple