Moving around in Turkey is a big issue for foreign tourists especially because it is a very big country and the places of tourist interest are quite far apart. Public transport is available but may not be too convenient for people who are not from the country. That is the reason why renting a car and moving around in it could be the best option.
In Turkey
Car rentals will typically pick you from your airport. There are several airports in Turkey, so you need to specify which airport. Also, some companies have free airport pickup or drop off. For example, Turkeycarhire.com allows for free drop offs for Antalya and Dalaman airports. This saves some amount on the total rental.
Renting Cars
Another important thing you must know in advance before you book the car is where you will have to drop it off. Typically, you drop off rental vehicles from the point you hired it, unless it is a chain of rental outfits. For instance, Webcarhire.com is a large group working within Turkey. They have a one-way car rental scheme. When you enter Turkey, you can rent your vehicle from the airport, then do some self sightseeing in the vehicle and then drop it off wherever you are returning home from. There are points in almost every city where you can return the cars. This is good for adventurous travelers and also otherwise, since you do not have to retrace your path and can make the most of the travel.
Check out for your Turkey car rental bookings before you land in the country. That is essential because when you are in the country, you might not know where to ask. The two websites mentioned above are quite good. Some others are CarrentalTurkey.com and RentacarTurkey.com.