Anything that should be at the bottom of my list or I should watch out for when I'm in Istanbul?
Yes, Ernest. The taxi drivers. Some of them have fixed meters so they charge much more than what they should do. I've used taxis a lot there but had only one incident of this, which ended in a heavy argument about the price. So always ask at the hotel what the price should be approximately when you're heading somewhere. Of course traffic, which is horribly slow, can have a big impact on the price, but still the swings should be within maybe 25%. Not 400%. The metro is most efficient if that fits the route you're going.
Other than that, just enjoy this magnificent historical city :)
oooo to answer your question would take a long time! May I suggest you invest in reading a guidebook for useful advice on what to avoid. But here's a summary:
Be weary of taxis that stalk you on the street. Always get a taxi from a taxi rank or ask your hotel/restaurant to order one for you. The meter should start at 3.20TL (price as of May 2015) all times of the day/night. Never haggle for taxi price, always use the meter.
Be ware of crowded areas and keeping your personal belongings safe.
Try to use ATMs on weekdays when the banks are open - just incase you have any problems with your card...unlikely, but just a safe guard.
Take the normal precautions you would in your own hometown.
Rather than bottom of the list - the priority sites should be Hagia Sophia, Blue Mosque, Topkapı Sarayı, Spice Bazaar, Grand Bazaar, Chora Church, Galata Kulesi, Istiklal Avenue, Bosphorus Cruise and Asian side (Kadıköy/Moda Cd is best). There are just too many sites to say what should be bottom of the list and will it depend on your interests...which you haven't mentioned.
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You had better go to Rahmi M. Koç Müzesi. It's very interesting museum in Istanbul. I advice you...