It's always a good idea to plan ahead for some things, and just wing others. However, you can really do yourself a favor and even save some money in certain cases.
DO:
1) Get your visa when you land in Turkey. It's the easiest thing in the world and takes all of one minute. As they see your passport, they hand you the visa and you avoid the long lines at the US embassies.
2) Try to go off-season; rates drop dramatically from the second week in October to the third.
3) Use your mileage if you have accrued a sufficient amount. American is affiliated with Turkish Airlines. It is also affiliated with British Airways, so you can take AA to Heathrow, tranfer to BA for Istanbul.
4) Watch your money! Sreet hawkers are very clever and in handing you something, they expertly slide your bills into their hands.
5) Bring a calculator; you'll need it at first to translate your dollars into lire and vice versa.
6)Remove your shoes and cover your head when entering a mosque. If your arms are bare, wear a shawl. Men, shorts are frowned upon.
7) Drink bottled water only. Although they claim that Istanbul's tap water is safe, it is usually recommended that you stay away from it.
8)Do get a receipt or invoice (fattura) for any goods you purchase as you may be asked to show it upon leaving the country.
9)Bring toilet paper with you.
10) Ask to see your room at a hotel before you accept it.
11)Bring an electrical adapter; voltage in Turkey is 220 volts; for your own 110 volt electrical appliances you'll also need that transformer.
12) Jot down the address and phone number of the American Embassy in Turkey; it is 110 Ataturk Bulvari in Ankara (the capital); tel is (312)468-5110. Alternatively, the American Consulate in Istanbul is at 104-108 Tepebasi, Beyoglu; tel # is (212)251-3602.
13) Stay hydrated, especially if exloring archaelogical sites, wear hats or other protective head gear.
14)Prepare your own first aid kit before leaving home.
15)Use your ATM card to get the absolute best exchange rate; machines are found in most banks.
DON'T:
1) Take pictures of people without asking permission first. You'll find most Turks eager to pose, but women are very protective of their children and believe in the evil eye.
2)Wear provocative or revealing clothes; you will invite unecessary attention and offend people around you.
3) Respond to children beggars; they are very persistent and will follow you around. If you wish to shake them off, just say "gendarme" and they'll stop pursuing you.
4) DISCUSS THE KURDISH QUESTION.
5)Pay the price any seller asks for, especially if he's got a salesman in on the deal. You will need to bring the price down to at least 60% of the original asking price to feel you have struck a fair deal.
6) Rely on any vendor to ship your purchases to your home. Make the shipping arrangements yourself.
7)Drive in Turkey if you can help it. Just watching the natives drive will dampen your enthusiasm.
8) Make telephone calls from your hotel room as the charges are unrealistic; you are better off using a phone card at the post office.
9)Wait till you get to your destination to pay your cab driver; establish the price before you board. We had one cab driver who was completely clueless and short tempered.
10)Publicly display affection for a member of the opposite sex.
Happy Traveling!