Turks are generally a welcoming race of people, eager to help and proud to show off their country. Sometimes the help can become overbearing. People here, once they've assisted you in any small detail, almost instantly expect something in return, and in a country where inflation is skyrocketing, this "return" normally involves the instant demand for money. Be prepared to pay or to trade for your services. Haggling and swapping and even price gouging are hardly confined to the Grand Bazaar.
I never did tip at resturants but then theydo include it in the service charge. Be nice and smile to people greet them by saying hello and thank you in Turkish and you will find Turkish people are very pleasant and hospitable and warm people.
As you can see from the pic the tall guy is Bora a VT member who lives in istanbul and the short (handsome) guy is me.