Check any copper grease is the high temp variety or you will have problems - otherwise fine as long as kept away from pistons.
Anything in contact with the rubbers should be lubed with red rubber grease (lightly) or the rubbers go to mush.
Pistons should only be lubed with brake fluid - anything else and the outer seals will start to bulge and jam the pistons, I speak from bitter experience.
ACF50 is good on the outers and esp. the nuts and bolts, but as stated it creeps, so it's best wiped on.
If you use one grease use the red rubber stuff - it's bloomin' sticky though.