In Moffat turn off the main road down the A708 towards Selkirk, the road is like the mad mouse till the bird sancruary (as said, slow right down for the bridge) then its up the mountain road, once up the top it opens out and is more predictable heading down past St Marys Loch, theres a café at the bottom of the hill on the main road by the loch at Tibbie Shiells Inn, a good place for a break...
After that its a flip of the coin whither to go on to Selkirk or turn left and go up the B709, brings you back up to the Peebles road, both are good...
Sorry, pix are nice, it looked good day...