If you are away from your own city or country, if you do not have a friend or family member abroad, the hotel would be your home. You used to ask for information to the friends who used to stay in the hotels before.
But thanks to the technology that is developing today, it is possible to get information and make reservations without going to the hotel. It is possible to access information from internet sites such as comments from previous customers, photos of rooms and other areas, whether there are vacant rooms or not and room prices.
You need to ask about Istanbul to the person who lives in Istanbul
To know the best hotels in Istanbul, you need to live in Istanbul; otherwise the only option is to ask someone living in Istanbul. Perhaps each hotel has its own website or you can access all kinds of comments and information on tourist sites; but the real tips of the best hotels in Istanbul can only be found on the PropertyTR web site: https://www.propertytr.com/best-hotels-in-istanbul-37-new