In the cities, in general, people dress just like anyone from the United States. Jeans and t-shirts are very common, although it does seem that people take a little more consideration of what they wear. Sweatpants and sweatshirts were not nearly as common on my Turkish campus as they are on the US one.
The one exception to the "just like everyone else" dressing can be found among girls who are religiously minded and choose to express this in their clothing. Religiously minded boys might also have a slightly different dressing style, but in general girls are the most noticeable. This is because these girls (known by various names - turban girls, covered/closed girls, or tesettűr girls) generally wear a headscarf.
I never took any pictures of them for some reason, but I found this one of the internet. It is a fair example of these girls. They are quite fashionable and the headscarf fashion is a big economy in Turkey now. Girls like this dress very nicely and their scarves come in all kinds of colors and patterns.
I never took any pictures of them for some reason, but I found this one of the internet. It is a fair example of these girls. They are quite fashionable and the headscarf fashion is a big economy in Turkey now. Girls like this dress very nicely and their scarves come in all kinds of colors and patterns. Next, I have an example from the Mersin/Adana region. This man is wearing what I call "tent pants." I know that is not the correct name, but I couldn't find out from anyone what the Turkish word for them was.
Now, I find this unique because in the southeast near the coast, I only saw men wearing these pants, but in central Anatolian villages, a lot of middle-aged and older women wear pants just like these but sold in softer, more patterned fabrics!
And, moving eastward we come to somewhere between Kars and Van. I saw several women with their scarves tied like this. In general, I only saw plain white scarves in two places- the easternmost cities and Cappadocia.
The women in the east wore white scarves layered around their heads and then secured with another colorful scarf like a crown. I am not sure, but I think I heard someone say that the colorful scarf can be (or historically was) used to mark which family a women came from. But, that's completely uncertain.
And, moving a little further south to Doğubayazıt, this man is probably Iranian. I saw only a very, very few men wearing headscarves like this one.
When I asked our guide he said they were not common and that probably he was not an ethnic Turk. BUT, he was still in Turkey, so it counts!
These next two pictures come from a very small Kurdish village near Van. The woman was baking bread. There was another woman with her and when she noticed us taking pictures, she
made sure her scarf was properly positioned. 
One guide said the little girl was dressed for a wedding and then another said this was a normal way to dress for Kurds. I am not sure which is correct, but seeing as I could hear a wedding party proceeding, I tend to believe it was for the party - especially since the other children in this picture are dressed "normally."
And, lastly, back to the center. This woman was walking through a small town in Cappadocia. I saw four other women dressed like her and it was the only time I ever saw women with a long, free flowing white scarf like this and then another, smaller one to cover the face.
In these pictures, some of the faces are blacked out either because I was not able to ask for permission or because I do not want to break the subject's code of modesty. In others, nothing is blacked out because the subjects were clearly comfortable with their attire and walking in a public area.
So, you can see here some of the diversity that Turkey encompasses. And, each difference in dress is also characterized by differences in opinion, culture, maybe language, and background, so the society is really facing a lot of issues when trying to come to terms with its heterogeneity.