The worst mistakes people make when getting a tattoo include choosing a tattoo that is the wrong size for the body part it is intended for, opting for a cheap tattoo and choosing a romantic tattoo that may last longer than the relationship it memorializes. HowStuffWorks points out other mistakes, including getting a tattoo on impulse or when intoxicated.
People sometimes ask for very small tattoos thinking they are cheaper. However, a tattoo that isn't the right size for the body part tends to look out of proportion, especially as skin ages and loses its elasticity.
In getting a cheap tattoo, a person runs a double risk. The tattoo may end up looking bad, and there is a higher risk that the tattoo artist was reusing needles or working without following proper disinfectant procedures, which can lead to hepatitis.
When people get tattoos using the names of their current significant others, they run the risk that the relationship may not last, leaving the tattoo out-of-date and emotionally painful. One well-known example is the tattoo "Winona Forever" that actor Johnny Depp got when he was dating Winona Ryder. After they broke up, he had to have the tattoo changed to say "Wino Forever." Tattoo artists typically warn clients not to tattoo any names other than those of their parents or children.