Kind of parroting what some have posted already, but when I work on any bike with a freewheel hub (or any wheel with a freewheel hub) for the first time, I always start by removing the freewheel, checking that the axle is centered properly left to right, and isn't bent. Then I tighten the driveside locknut(s) firmly against the driveside cone.

I've seen hubshell cups cracked from a driveside cone having spun itself inward, so driveside axle hardware must be sufficiently torqued to prevent self-tightening of the cone.
Left-side pedal bearings similarly tend to self-tighten if the locknut isn't tight enough against the cone.