First you have to focus on the subject. I focus by swinging the rack and pinion focuser back and forth until I get the sharpest image in my opinion.
Then, the photography settings - I usually use an exposure of 1-2 seconds max to reduce star trailing. ISO is cranked up to the region of 1800-6400.
Below are some of the images I've taken through prime focus. You may have seen them on facebook but here it's much clearer :)
