I'm having some doubts on what colors I should choose. Let's say you have a tshirt and a long sleeve, where you can only see a bit of the crew neck of the tshirt. What kind of tshirt color would you chose?
Something that matches the one on top (eg. green long sleeve and green tshirt, blue long sleeve and blue tshirt), or something that is completely different (eg. green long sleeve and white/black/gray tshirt) or even complementary colors (eg. green long sleeve and red tshirt)?