The three throat positions account for six letters. Recite them in order to remember the progression from the deepest region toward the mouth.
Deepest: ء، ه.
Middle: ع، ح.
Nearest mouth: غ، خ.
First articulate each one in isolation. Then compare commonly confused pairs: ء / ع, ه / ح, and ح / خ. The paired drills do not imply that the letters have one exact point; they train the ear to preserve their differences.