The Abbey Craig is very easy to find, as you can see the Wallace Monument from miles around. If you can find your way onto the A9 in the centre of Stirling, heading N on the dual carriageway section, then at the roundabout next to the bridge over the Forth, turn right. Head along past all the B&Bs until you come to another roundabout, which you want to go straight over and up the small B998. The road doubles back on itself as it climbs the hill and you will soon find yourself at the car park for the Wallace Monument.
Watch out for the hideous statue of Mel Gibson (no really!) dressed in his Braveheart garb.
From the car park, just follow the path up to the Monument.