Park in the main parking lot for Hanging Rock State Park, and the trailhead can easily be found in the upper parking lot (furthest away from the main building), and is clearly marked. The trail starts off by descending, but don't be fooled, it quickly turns into a steady climb that will have you wanting to catch your breath in spite of the relatively short distance.

At about the one mile mark, you'll reach a set of man-made steps, and after climbing those you'll catch your first glimpse of Hanging Rock directly overhead. From here you'll make your final push around and to the top, coming in from behind Hanging Rock. 

I was lucky enough to hike there on a weeknight, and had the place nearly to myself. However, the weekends will be very crowded and heavily trafficked. But there are plenty of boulders and overlooks for you to find your own little spot.