Start from the twenty-mile ranger station off of North Carolina 28. There is parking for vehicles 150 yards past the ranger station. Start the route on Twenty-mile trail. The standard GSMNP map will show the ranger station and all of the trails.
Twenty-mile trail will lead you to Long Hungry Trail that is appropriately named. These two trails follow streams along abondened road beds and are easy hiking. Long hungry trail will finally cross the creek (no foot bridge) and ascend at a greater incline than when following the old roadbeds. Eventually you will intercet with Gregory Ridge Trail, to the right, about two miles, this will intersect with the AT. You want to go left and this will lead to one of the steepest climbs on this loop. This incline will bring you out on Gregory Bald. After enjoying the views, continue on off the bald headed to campsite 13. This campsite requires reservations. Continue West-South-West to Parsons Bald. This bald has mostly grown up and offers little in long distance views. At the South-West end of the bald you will pick up Wolf Ridge Trail. Wolf Ridge will take you back to Twenty-mile Trail and lead you back to the parking lot.
Map, compass, GPS, etc. Comfortable hiking shoes or boots. There are several stream crossings that can normally be rock hopped. Plenty of water. If you filter two, liter bottles will get the job done. Rain Gear, the Smokies are in a rain forrest! Trecking poles. Clothing that is seasonal. The bald is often 20 or so degrees cooler than the trailhead and at times there are wind gust that will blow you over. I never go without some fleece to wear under my raingear.
You will follow creeks for the first and last third of this hike, so water is available but since you are in one of the most popular National Parks I would bring a filter or Iodine tablets. There is a spring to the south of Gregory Ridge Trail and this can be found on a good map. A small stream flows across the trail that leads to Parsons Branch Road from Campsite 13. It will be an additional half mile round trip if you get water from this source.