Signage on Great Northern Road

I don't think you'll get lost, there are enough signs about the place.

For the ride you have indicated, if you can find your way to the bottom of Devine's Hill (suggest parking on the Sydney side of the ferry near the kiosk, go over on the ferry, turn left and you can't really miss it), there is OK signposting of Shepherds Gully (at the top of Devine's Hill) and when you get to the Western Commission track (the end of the "old" section). From there it's pretty much downhill dirt road to Ten Mile Hollow and a km further to Clare's Bridge. Can't remember if the bridge itself is clearly signposted, but it's not the wooden bridge you come to just after the Buddhist monastery, it's a bit further on (and there is no bridge, just the sandstone supports).

Then turn around and head back, turning off to Shepherds Gully before the gate at the the top of Devine's Hill (it's a few kms on the tar back to the ferry though, so if you're toasted, walk down Devine's Hill).

If it's hot, take plenty of water. The Buddhists have had a water drum out beside the dirt road for refills (saves people pestering them to use their water tanks I suppose), but I haven't been up there for a few months and otherwise it is pretty dry - which is why that route was abandoned as a coach / dray route to the Hunter pretty much as soon as it was completed.