u press "t" . Then you can set a machine to pot for you when your hp / mp reaches certain levels. Check the hp / mp box, and set the % to where you like it. You can also set it for abnormal status. Adjust the place on the hotkeys, and put your hp, mp, and universal pots and pills in those slots. Then, test it out on some weak mobs. They should be strong enough to get you down to that hp, but weak enough that you can easily survive by manually potting.
Auto pot helps a LOT, especially when you are mashing keys for skills and its tough to click the pot or press the number all the time.