For yellow, I prefer counterclockwise from the northernmost entrance (off Gilbride), then cross over Miller lane at the top and keep riding down hill. Then up toward the new "Hi Tech" trail where it starts near teh intersection of Miller and Voseller and do that clockwise (mainly downhill), and up again and cross back over Miller to finish off down the eastern leg of yellow.
For Orange, I prefer clockwise...either riding the trail along the stream, or the upper trail. The former is a tougher slog.
Good luck, Chimney is fun no matter what direction you ride.