While hearts and stars may lend themselves to girly swirl designs, you may also consider the swirly possibilities of the elements. Make fire feminine with elegant swirls. The flames might even blend in a yin-yang motif with swirly waves of water and serve as a backdrop for a goddess tattoo, whose hair and clothing swirl majestically around her.
Swirls can be manly, too. They can accentuate the curves of a motorcycle or a muscle car. The smoke or flames from the exhaust might swirl around the muscles in your arm or chest, subtly accentuating--or exaggerating--their bulk.
Swirl patterns can create an other-worldly effect in landscape tattoos. If you're considering a large tattoo that depicts a fantasy environment, study the swirly patterns in the artwork of movie director Tim Burton or the painter Vincent Van Gogh.