To reach the falls you have to take the Inverkirkaig road south from Lochinver and park at a small paved parking area just before the bridge over the river. There is a signposted trail beside the driveway to the Inverkirkaig Hotel. The route starts on a paved path but quickly changes to a rough track.
The trail runs along the River Kirkaig at first, and you can catch glimpses of the river through pleasant woodland. Then the ground rises and you emerge onto open moorland. There are marvellous views east along the glen, and you can see the river rushing ahead down on the valley floor.
This is where I usually insert a warning about the need for good waterproof footwear; consider yourself warned! The going is not difficult at all but can be wet and muddy. Don't even think about walking to the Falls in trainers, like the delightful German mother and daughter I met, who seemed like they were dressed for an outing on Regent Street rather than a Highland walk.
At length, the path divides. The signposted right fork takes you down to the Falls, while the left fork proceeds towards Suilven. From this point you really do need to take care; the rocks can be slippery with water and mud, and as you approach the falls the going gets extremely wet. There is no fencing for safety, so please use common sense and do not go too close to the edge. The drop down to the river is precipitous, but the view is spectacular, and the Falls are dramatic and the noise is thunderous.
The walk to the falls is just over two miles each way. Count on three hours there and back. Use the OS Explorer map 442 Assynt.