Ok, let's keep this to dandexter's model.
It looks ok. The top of the rib cage is very sharp though. It's a good idea to make the edges flow with the shape of the body. For example, make the edges flow from the sides of the rib cage, flowing up the stomach area, then between the breasts. Taking a look at muscle anatomy, as well as skeletons will greatly help you.
What I would HIGHLY recommend, would be to find some images on the internet, that shows muscles, forms, and other anatomy. Good ones are artistic nudes, or nude gymnastics. Practice drawing edge flow on these images. Follow the forms, the bumps, the curves. Don't worry about how you'll make it work. Just follow them with lines.
Once you are done, try and connect those lines into logical ways. Use these images as your base for your topology. It doesn't really matter how you start your model, as long as it looks good. It's all personal preference, and you need to find the way that works for you. For me, it's all box modeling. For others, it's patch modeling. It doesn't matter. That's the great thing about organic modeling, and 3d in general. It's completely free! Just do what you like, and what you find is fun!
I would also recommend not smoothing your model until you can see the shapes in the low poly version. It will help. Not sure why, it just does :p
Keep going mate!
Imagination is more important than knowledge.