We went up to Lake George in June 2017 form the Jersey Shore. From your location I would suggest the NJ Turnpike to I287 to join the NY Thruway and the Adirondack Northway (I87) all the way to exit 20 for route 149 - Fort Ann & Whitehall.
From Exit 20 it was a left turn at a traffic light then about 1/2 mile to a right turn onto 149. Traffic was bad in this area due to a number of outlet stores in the section between the exit and 149.
FYI, we stayed at King Phillips Campground a mile or so further north.