For the Upper Campsie Glen I parked in the main car park on the B road from Lennoxtown to Fintry. There's a good path and stepped descent down to the plunge pool of the first of a series of falls.
After that it's scrambles around each fall and a hint that someone might have walked up the rough grass some time ago once the trees stop!
When the trees stop it's a moorland valley. The B road is high on the right.
Nice flat rock for a picnic:
When I got up to where the stream joins the road I found I had actually been walking an "informal route". Very informal methinks, excellent:
Walked back down the road to the car to have a quick look at Jamie Wright's Well