If flying in IMC and icing occurs - immediate 180o turn and bug outta there.
It always amazed me that when hundreds of DC3's from the war were made available to civilian operators in Australia, one of the first "modifications" these operators made was to strip off the wing and tail rubber de-icing boots. This was done to save weight and make more money. DCA looked the other way and even approved the modification.
So for years there were DC3's and Bristol Freighters and other smaller twins and singles being flown in southern Australia and across to Tasmania hauling freight and passengers in mid-winter while braving ice. Sure there was sling rings to throw de-icing fluid into the props and squirty stuff to de-ice the cockpit the windshields. But the rules designed to prevent flying in icing conditions were regularly flouted and are still flouted to this day with Chieftains and their GA ilk which are not equipped for flight into known icing. There were many frights as aircraft were covered with ice but most managed to get away with it although the number of close calls were never recorded. The good old RAAF did the safe thing and kept their Dakotas with the rubber de-icing boots installed - and still did until the last Dakota was retired.