Beginner looking for help (not scratching)

Hello, I've decided within the past year that i want to pursue a career as a tattoo artist and am looking for some specific tips for beginners. I'm not tattooing on anybody and don't plan to, but I have some questions about flash. What does everyone use to color/ outline with? I've been using prismacolor pencils and faber castell artist pens for outlining. Is most flash done with pencils or something else? Also, what about shading? I'm having a hard time getting the grey tones I'd like simply from a black pencil. Sorry if these questions seem basic, but my background is more with painting. One last question. Does anyone know of any books covering shadows/ highlights with geometric shapes. thanks in advance. Any other tips are appreciated.

Hey, dont know much on the flash side of things, only year and half done of an apprenticeship myself but in terms of books about art etc....on amazon there are some great books b burne hogarth, the dynamic light and shade book is the best apparently but you will also find other books by different artists on burnes amazon page...... sound like your starting the right way....you cant be a great tattoo artist when your a shit artist hehehe.gota brush up on those art skills....good luck !!! :-D