Really enjoy the crisp lineart and simple coloring (that's often standard for tattoos, but still~). For some reason, the color scheme reminds me of comics from the 80s, especially the olive-yellow color for the skull and the washed out blue for the hair's highlights. The texture from the brush lends a definite tangibility to the outlines, and I like the stippling effect used for depth. Also, I'm a fan of skulls, so that's another plus from me. I hope your friend loves it!