The only way to explore Naoshima is by ebike. It may be tiny, but it is hilly, so the electric motor is a good choice.
Dotted around the island you will find sculptures, galleries and architecture from the greats, including; James Turrell, Tadao Ando and Lee Ufan. There is no top list for Naoshima, you must see it all, it is just too good.
And after a day of peddle power, there are tiny coffee shops and cafes for your caffeine and Japanese curry fix.