Going to change fridge starter relay and capacitor. Any gotchyas to look out for?

They may hold a charge. It is not usualy dangerous unless you grab each lead with each hand so the currrent passse through your heart area, but it sure can make you hirt yourself. Take a screwdriver with a plastic handle and short across the leads or terminals of the capacitor you are taking out. The new one will not have a charge on it, just the old one that has been plugged in may have a charge, but probalby will not especially if it has been off for a few days.