A few of the known parking locations

Windsor

Windsor Center- corner of  Rt9 & Peru Rd. across from the post office.

Windsor Rod & Gun club- 100 yards west of Friendly Fred's store, Route 9.

Wahconah Falls State Park- Route 9, 2 miles east of int. Routes 8& 9, Dalton.  Only go down there if you have 4 wheel drive.

Pittsfield State Forest- Parking lot near ski jump (Cascade Street).

Cheshire - On route 8 across from Bedard's Auto gives access to North Mountain (trails to Savoy and Windsor). 

Across from Bass Water Grill gives access to Cheshire Lake.  There is not a legal crossing of the rail trail.

Mount Greylock - Parking lot at the visitor center off Route 7.   Follow signs for Mount Greylock State Forest.

Pontoosuc Lake Boat Launch - On Hancock Road, just off Route 7.  (Need to have ice on the lake to access trails.)

October Mountain State Forest -  At Bucksteep Manor, Washington Mountain Rd., Washington, MA.  
If you are coming from Mass Pike, you might also check out the state parking lot in Lee, MA, just follow signs for October Mountain State Forest.