Twi’lek’s have a rainbow range and more in coloration, they can be any shade of red, green, blue, purple, pink, yellow, and much more. These skin colors can come in modeled combinations or solid.
Twi’lek’s typically have lips colored differently than their bodies, however, sometimes a slightly darker version of their body color. Sometimes their lips are the same color as their body, this lip coloration patterning is the same for both female and males.
Twi’lek’s body colors can also include modeling, both male and females can have modeling, typical of two colors. Such as Cham Syndulla who has orange and cream modeling that almost takes on a semi striped pattern, though it should not go as far as actual strips. (See: green and red arrows for modeling, blue rectangle is tattooing.)
Other modeling appears blotchier such as the little Twi’lek girl in Star Wars The Clone Wars: Season 2 Episode 10. Blue and pink modeling appears in her body color, (see: green and red arrows.)
The patterning that appears on many of the Twi’lek’s does not appear to be tattoos, Aayla Secura has light blue specials/dots on her Lekku. Patterning is similar to modeling, however, patterning does not always or even typical cover the entire body, where as modeling typical does.
Other Twi’lek’s have speckling patterns on their bodies and Lekku such as the blue senate Twi’lek. She had a lighter blue speckling on her Lekku and her arms,
Hera has skin patterning of a lighter green circular patterning on her Lekku only, similar to Aayla Secura.
It seems that only Lekku being patterned is the most common variant, there is a range from no patterning, to just the Lekku, to the Lekku and body patterning. The most common variation for Twi’leks is to not have any patterning at all, such as Oola or Numa (see picture below.)
Suu Lawquane, the mother of the little Twi’lek girl with modeling, that appears in Star Wars The Clone Wars: Season 2 Episode 10, has dark pink patterning over her entire body in a dotted-spiral and circular pattern. It is also possible that Suu Lawquane’s skin patterns are actually tattoos.
Tattoos and Scars:
Cham Syndulla has tattooing over his Lekku and face, other Twi’lek’s also appear to have tattooing. As above mentioned, Suu Lawquane might have tattooing instead of pattering, Darth Talon is an example from the Legends EU of a Twi’lek with tattooing.
Images from Cap-That.Com