This is (from what I've read) the most common way of approaching Orno and NW Orno. It is not, however, very short or easy.
See the main page. Park at the TH indicated by the waypoints.
Follow the well established trail into the Flat Tops Wilderness until you are below Mandall Pass. From there, you have to head NW on a very faint trail connecting the dots of old upright posts to get to the trail of Mandall Pass again. Ascend to the pass, then either head north to NW Orno or head east to Orno Peak. Return the same way.
Be prepared for weather. Water is available along the hike, but must be filtered. Bring plenty of food/snacks and sunscreen. The areas along the trail also make for great campsites.