Marmara, Aegean and Mediterranean coasts: Light, cotton summer clothing and cardigans for evening.
Black Sea, Central and Eastern Anatolia: Summer wear, warmer clothing should be taken for cool evenings at high altitudes.
Comfortable shoes are necessary for visiting archeological and historical sites.
Sun hats and sunglasses are advisable in the summer.
Headscarves should be brought by women for visiting mosques
Source: (Wikitravel)