So far in December there are 19 murders in Chicago and I bet there will be 2 more before this day is over. All of them in one of 7 neighborhoods (5 zip codes), none of which are "tourist centers". All the victims were residents, all were of a well defined socioeconomic group. Statistically the vast majority were murdered by someone they know - not strangers, and the crimes were related to criminal activity. Not becoming part of that statistic group is easy; don't participate in criminal acts, don't associate with those that do and don't go to high crime neighborhoods that serve no interest to tourism.
On the other hand the blast in Turkey today injured and killed complete strangers in an area adjacent to Taksim Square which is a place where one might find tourists. So how to increase your odds of safety in Istanbul? Stay away from tourist centers and mass gatherings and any police presence (as the police seem to be the main targets).
I do live a blessed life and I have to remember that those that feel safer in Istanbul than their US community have different life experience than I do. The crime statistics in the major US city community where I live and work are a fraction of the statistics for any major city in Europe. So I am always safer at home.