It's a question of personal taste. Looking at current trends, the biggest demand is for tribal designs such as Maori or Polynesian. It's not surprising when you learn that tattoo comes from the Tahitian word tatau, which means "drawing". Butterflies and fairies are also attractive designs for fashionistas. You can have a tattoo and still be feminine, right?
However, getting your boyfriend's name inscribed on your body in permanent ink is NOT recommended. You just never know, the relationship might not last as long as the tattoo...
It's also best to avoid declarations of love for your favourite celeb or group. You have to feel for all those who had the Boyzone logo tattooed on their bodies in the 90s! If you're going to pay hommage to someone, it's best to choose a timeless icon such as John Lennon, for example.
Above all, make sure you think it through properly and ask yourself whether you'll be happy showing off your tattoo in every circumstance: at a job interview, at your great-uncle's funeral, at Sunday lunch with your future in-laws, at your grandson's birthday party in 40 years' time, etc etc.