We have to admit that employment opportunities for foreigners are not very large in Turkey.
Let us say first that foreigners who are married to Turkish citizens or who have obtained Turkish citizenship are not restricted by the employment laws, on the condtion that they do speak fluent Turkish.
Most foreigners working in Turkey work at Turkish branches of foreign companies, foreign embassies, or NGOs. Those who do not work at those institutions and try to find job at private sector might have a tough time earning a living. Teaching and tourism are the basic sectors with the most openings for foreigners are
There are many language teaching jobs throughout Turkey, however it is hard to say that they pay extraordinarily well, but nevertheless they offer enough money to survive. Being a fluent English speaker, you might be able to work giving private English lessons.
We might say that working in tourism is financially much tougher: while English-speakers are mostly demanded, most employers (at least in restaurants, bars, and other shops) do not offer much more money than it takes to cover the cost of living. Works in hotels and at resorts pay better but are less common.
Foreigners can work as journalists and nannies in Turkey, though journalism jobs are relatively uncommon and nanny positions can be very demanding.
Fluency in Turkish is a major asset If you are working at a job in Turkey.