When trying to take star trail photos in the southern hemisphere you look for the south celestial pole. The reason you look for this is that is the point in which the stars rotate around forming the circle.

Accurately finding the south celestial pole isn’t easy, well for me anyway. You can ‘draw’ a line through the head and foot of the southern cross into the night sky and then ‘draw’ a line perpendicular out from the pointers. Where these two lines intersect is the south celestial pole. As you can imagine, I don’t always get my ‘drawing’ correct.