[Superman]

Adjust the clutch. Make sure the Bowden Tube arches over the throttle linkage.

New clutch cables help a LOT.

Make sure your motor mounts are in good shape and are not loose.

New clutch disk.

Make sure your transmission input shaft seal is doing its job. Oil-fouled clutch disks are usually fouled with transmission oil, not motor oil. Engine rear main seals rarely leak and if they do, they foul the rear-side of the flywheel, not the clutch disk. Transmission input shaft seals, when they leak, they allow oil to crawl up the input shaft and get directly onto the clutch disk.

But again, the first things to look at are cables and cable adjustment.....and motor mounts. The bad news here is that nine times out of ten, it's going to be a wet clutch disk.