This question rises in head of everybody who just bought turtle. Many people buy them before planning it first. That's the reason why they ask themselves this question. I was one of those people. When I bought my turtles, I knew nothing about how to feed them. Luckily, saleswoman gave me some advice so I bought right food for them on the spot.
Anyway, you should plan first and act later. It's always good to know what species of turtle you want to buy eats. Different turtles may like different foods. Reading some specialized book is always good and you can only profit from it. However, I must say, that not all information you find in a book is valid for every turtle of certain species. After I bought my turtles, I've bought some books about that certain species. All books said that my turtles should like meat, vegetables and even fruit. In my case, the written fact was one thing and reality other. I tried to feed my turtles with the food saleswoman sold me. They liked it. When it was feeding time again, I decided to feed them with something else. I tried many kinds of vegetables and fruits. According to books I bought, they should have eaten it. However, they haven't even touched any of vegetables and fruits I gave them. So I had to take the original food and feed them with it. However, after about two years of eating it, they stopped eating it. That was the reason why I started to feed them with meat. I tried fish, fowl, beef and even pork meat. Again, according to books, they should have gone for fish. However they've chosen pork meat.
Result of my experience is that no matter what book says your turtles can have their own taste which can differ from advice given to you in a book. All you need to do is try different natural food and your turtles will choose what's good for them. Anyway, reading books about your turtle species will at least give you an idea about feeding them. You should also search for some food adjuncts. Turtles, especially young ones, will probably need some additional vitamins and substances to grow up properly. To find such products, it's best to ask your veterinary or salesman in some specialized shop. However, I'd recommend the vet.
