a few things i do-
grease seals before install, especially the crank seals.
seal the key on the crank
loctite on the crank nut and clutch basket nut and tighten both with an impact.
grease the rod and ball and clutch pusher
grease the clutch arm bearing
put a little oil in the crank bearings through their oil holes before top end install.
i like a soft scotch brite pad to clean gasket surfaces while i have them in the parts washer.