The first thing to say is that when interfacing with a client or other stakeholder in Turkey it is important to consider the national origins of the parent company. Many multi-nationals have operations in Turkey and when dealing with the subsidiary of an international company, it is likely that that subsidiary will have taken on at least some of the characteristics of the culture of the head office.
Traditionally most indigenous business in Turkey has either been family-owned companies or state-owned enterprises and, as can been imagined, these companies have tended to be extremely hierarchical in nature with multiple layers of bureaucracy. Even in foreign-run businesses it is highly likely that you will encounter an increased level of hierarchy and this need to be factored in when doing business in Turkey.
As in all hierarchies in the region, decisions tend to be taken at the top of the organisation and it is therefore really important to put some research into who the decision-makers actually are. Are you dealing with the decision-maker or somebody who might be an influencer of the decision-maker? Take the time to analyse this carefully as it should have a major impact on your tactics when starting to do business in Turkey. If you are not careful, you can waste a lot of time, effort and money speaking to the wrong people. The nearer your conversations are to the top of the pyramid, the better chance you have of being successful.
It would not be too far from the truth to say that the strength of relationships you are able to build at different levels within a local organisation will be the key determining factor when doing business in Turkey.