Really, the main things to adjust in FocusMax > Preferences > AcquireStar tab are: (1) the initial exposure time, where 3-4 seconds is usually a good starting point; (2) the magnitude range in the filter you (and ACP) use to focus, where 0.7-1.0 magnitude between min and max is usually about right; and (3) the minimum altitude for the focus star, where most users find that 50-60 degrees minimum altitude from the horizon works about right.

When you've adjusted the magnitude max and min so that FocusMax AcquireStar consistently exposes for 1-3 seconds (depending on your camera's abilities), then you're usually good to go.