Old-school tattoos are known for being timeless with their bold lines and color palette, while Neo-traditional adds a little more detail and fun to the traditional old-school style. Whichever you prefer is up to you.
This is considered to be the original form of tattooing, and every other style origins from this kind of style – especially when it comes to technique and composition. This is often the first style to learn as an apprentice, next after simple linework of course.