First pick a tattoo that you not only like now but one that you will like in the future. Try to pick something from your life that you have always enjoyed. If you have kids these are a great source of tattoo ideas since you will always cherish your children. You don't have to just get names think of a design or picture that will always remind you of that special family member or someone.
Second make sure and speak to the tattoo artist before you go in for your tat. Ask the artist questions and review their books. Quality tattoo artists keep books not only of art but pictures of work they have done. This way you can see the final tattoo on someone's skin and better picture how it will look on yours.
Third find a tattoo that is individual for you. You don't want to pick a design off the wall and find that everyone you meet has the same tattoo. Combine tattoos to make one design, or cut and paste different aspects of a couple to form one unique tattoo. Also make sure the tattoo artist understands that your design is for you and not to be reproduced.
Finally make sure and take your time picking a tattoo. A life long piece of artwork is not something to rush into. Take your time and find the perfect tattoo that you will be happy with. That's what's nice about the internet being able to find huge online databases of tattoo designs and ideas that you can sit at home and view at your own pace without feeling rushed.