There are many different tattoo lettering styles, just like fonts for the computer. A good tattoo artist can recommend lettering styles depending on what type of tattoo you want.
I often see lettering tattoos and have to look and look to try and figure out what the letters say and it drives me nuts! What is the point in having a tattoo with letters that no one can read? These are generally very script type letters that are swirly, curly and scripts.