Set focus to a distant object like a tree (focus in the evening while you can see detail), then remember or set the position and aim the camera up. But not just anywhere up! Locate the Southern Cross. Next, place your thumb and index finger on the cross-beam (horizontal line of two stars that form the cross) and duplicate the length three times to the right. This approximates very closely the South Celestial Pole (which has the distinction of being around the 3,000th faintest star... ) around which all other stars rotate. This is the best effect but of course the location and contextual interest (tree(s), buildings, rocks etc) will determine how and where you set up. Keep the camera safe and yourself amused (and warm!) for 2 to 3 hours. f8 will give you more star trails but will need a longer exposure. I favour f6.7 to f8 maximum, no filters. Here in southern Victoria there is high streaks of cloud but that should clear up. I am planning star trails too on the weekend. Watch out for the moon (in last quarter). It rises at 11.51pm tonight (Friday). The moon, even a crescent, can turn night into day and ruin a star trails outing. New Moon nights are the best.