I've turkey hunted Green Ridge before...with some success.

Look for nearby running streams. Turkeys...especially first born chicks --- need water. Hens like to nest in brushy areas. Highway 68 traffic noise will sometimes drown out turkey gobbles.
On your topo map...look for a series of mountain ridges an saddles, that spread out about halfway down Green Ridge mountain. It makes it much easier going for both turkeys and hunters. And you can pick your choice of ridge to travel on, before you might hit private hunt club property.

Some streams like Maple Run might be dry...but they should still hold occasional exposed pockets of standing water.
Green Ridge Forest Headquarters sells good topo maps of the forest. Don't forget to get their phone number.
One turkey hunter...who gave a lecture on turkey huntin' that I attended --- had another hunter shoot at his turkey decoy at GRSF. Two shotgun pellets hit his camo netting that he was sitting behind. May I suggest...for good safety measure --- Put a tree between you and the decoy ---- that is...if you use one.
Turkey gobbles can easily echo off the ridges...so it might be hard to pinpoint where the gobbler's location is at times.
Coyotes in Maryland...have probably had a dramatic impact on the rate of gobbling.


Good luck...

Erno