Caution in this context is a care for the future of your sketch. That is, the confidence that it won't cease too soon. That's why you need to understand the basics. Those subtleties that only real artists know.
The Russian art school is one of the strongest in the world. Thanks to the classical approach, students learn in time about many features of the drawing, which surely become important factors of any image success. Chiaroscuro, contrast, reflection, palette, exposure, etc. - the balance of all these components allows you to give your client a timeless image that will always delight the eye. And this is extremely important for any tattoo because it's not created just for one year.
Ever since the days when I lived and studied in Russia, Moscow, my attention was riveted by the works of medieval artists, from the expressive classicism of Caravaggio to the mystical paintings of Francisco De Goya.