One thing i did forget to mention, when it comes time to get the tattoo, be sure to research, research, research... find the best possible artist for the type of tattoo you want...
Nothing worst than finding the perfect idea, getting all hyped up and then having a dodgy tattoo artist do the work for you and botch it up just coz you wanted to save a few bucks...
Coz as many here have already told you, once its on your skin theres no turning back... and if its a botched tattoo, even a cover up will not completely cover the mistakes made especially if the skin's all raised from said tattoo...
Oh, and this should be obvious, but make sure the tattoo artist uses new needles and sterilized equipment... since i'm sure you don't want to be picking up any nasty **** the last customer(s) may or may not have...