The finer lines really do make the biggest distinction between regular tribal designs and feminine tribal tattoos, but there is another route you can take to put a uniquely feminine spin on your ink work: the use of color.
Although you don't see this done as much, you can choose a color other than black for your design. Imagine a tribal tat done in sea green, peach, pink or turquoise; this will definitely give the design an entirely different feel. Although some tat enthusiasts might argue that this approach robs the design of some of it's power, isn't that exactly the point of it all? You need to refine your ink if you want it to carry a more feminine appeal. Your choice of color can do this for you.