Probably the best thing I have ever done to further my art and break the 'anime-esque' style was take a Drawing and Design class, where we were taught how to draw humans for about two weeks. Not a long time. But I had a teacher who near despises anime and manga style and draws with a style so unlike my own that I hate it. Yet, he taught me the importance of balance, composition, and how a human being really looks. He taught me how to measure properly. (six-seven heads tall, corners of mouth line up with center of eyes, top of ears line up with eyebrows, bottoms of ears line up with corner of mouth, that stuff) It was probably the best two weeks of half-arsed art I had ever done, but I walked away knowing something
My advice: Take a drawing and design class, one that teaches how to draw realistic people. A class is often more comprehensive and involving than a written tutorial (Not that you shouldn't use those). It will teach you how to see. Really see. You'll start seeing the world in a completely different way. People will become more interesting to look at. Your art will start to change a little. (mine did) It may not be completely realistic, but it's a start. It takes ages to get right and you'll probably be very frustrated mid-way through, but you'll get it.
Realism is a difficult thing because people know what people look like. Eventually you'll begin to see balance in your drawings. You'll know when something's off and when something looks exactly right. You'll often scrap most of your work repeatedly. One day, though, the work will pay off and you'll be happy with what you have. Photo reference is a wonderful gift, especially when drawing odd positions or strange angles. Use these things liberally.
Uh...I can think of a few more things that I won't add due to length. Any questions, just ask away.