"Clusters" is not commonly used about hair, although it is not actually incorrect. "Bunches" would be more usual, I think. "Ringlets" is the usual way of describing hair curled into sausage-like shapes. "Locks" means hair in general, the same as "tresses". I once did a crossword puzzle in which one clue was "distressed" - the answer was "unlocked". Clever, yes?