[CliffFletcher]

Istanbul is pretty much like a Southern European city in terms of cultural norms. So are the heavily touristed parts of Turkey. However, if you go into the interior you need to respect more conservative norms. Do not initiate conversation with women you don't know unless you're engaged in a commercial transaction. Do not sit down on public transit next to a woman you don't know. Do not act visibly drunk in public.

Go to the main tourist sites in Istanbul (the Hagia Sophia, Blue Mosque, and covered market) early in the day. They get very crowded. Venture across the bridge to the Taksim and Beyoğlu districts to get away from the tourist zone and see how the young locals live.

Avoid the street food. An expat I met referred to the bread rings sold at bus stations as 'hepatitis rings.' If you don't understand a menu, or don't find anything you like, restaurants usually display food under a glass case and you can just point to what you want. Sometimes a waiter will even take you into the kitchen and open a fridge and you can just point out what you'd like them to prepare.

If you're going outside Istanbul, take the bus. Unlike most countries, the bus system in Turkey is far superior to the train system. It's fast, clean, efficient, and very cheap.