Tattoos have been around for centuries. They were once used as a rite of passage, as a test into adulthood. It was said that if a girl couldn't take the pain of tattooing she wouldn't be able to withstand childbirth, and was therefore unworthy of marriage. For boys, being able to stand the pain of a tattoo meant they were good warrior material. In some tribes, tattoos are seen as an indication of social status or attractiveness. There are tribes in more primitive parts of the world who still share these views today, but for the more developed areas, the tattoo is simply a form of decoration on the body.
There used to be a stigma attached to tattooing; it was seen as a 'manly' thing to do, and very few women had visible tattoos for fear of being labelled harshly. But nowadays, more and more women are getting 'inked' and as a result, this permanent form of body modification has seen an increase in popularity and a reduction in stigma.
The lines between 'male' and 'female' tattoos are blurred; traditionally men went for the typical skulls, crosses and bulldogs while women chose flowers, hearts and cute animals. Such a stereotype isn't true any longer, ask any tattooist and they'll tell you they can expect to ink pretty much anything on anyone these days.
One style of tattoo which is popular for both genders is the tribal tattoo. Again, there isn't a particular gender-oriented style but female tribal designs lean more towards the curvy, flowing style than the more spiky, thorny look of one a man might favour. Often the female tribal design will intertwine with vines, flowers or butterflies, resulting in a feminine yet 'tough' look which can be extremely attractive, if inked well and in a good location on the body.
Tribal tattoos for women tend to use lighter and/or thinner lines, and often have 'sparkly' embellishments to them. Quite often they will form an abstract picture of a heart or animal, as opposed to a man's tribal tattoo which is often just a non-specific pattern.
Of course, there is no hard and fast rule when it comes to tattooing, and I mean no disrespect to anyone by attempting to stereotype any particular tattoo design. At the end of the day, a tattoo is a personal choice and it's entirely down to your own personality as to what tattoo you choose. I myself have several tattoos, some of which could be classed as 'manly', others which are more typically feminine. Remember, a woman can get away with having masculine tattoos a lot easier than the reverse!