Surely a player of your bridge skills is familiar with most or all of the following tips you are about to read. But is your partner?
When giving partner a ruff, the card you lead is suit preference telling partner which suit to return after the ruff. The return of a relatively high spot card asks for a return in the higher ranking of the two remaining suits. A return of your lowest card asks for a return in the lower ranking of the two remaining suits. The return of a middle card is designed to drive partner crazy. It actually means you have no preference.