The target of this project was to create a rigged character as real as possible and with all the clothes layers. This has been the first time I do something like this, and also the first time I tried to do a full human character, so I also used it to learn a lot.
There's really not too much to explain about the modeling. It's all always the same tools: extruding edges and polys, cutting edges, moving vertexes... These are the basics that everybody can learn from the famous Joan of Arc tutorial. Once you have that basics, I think what is more useful to learn is to see the wires, so here you have mine. You can see some parts have more edges than the normal, but that's cause all the rigging stuff I wanted to add. For example, if you look at the hips, I added some edges just to make the flesh deform correctly when she's wearing the underwear, or if you look at the ribs I added edges to create them but in the modeling pose they are not visible, I just make them visible when she's bending back. That's, imo, probably the hardest part about modeling, knowing where you have to put the edgeloops and knowing what you will need when rigging. It's just planning it before start to model.
During the wip of this project, some people asked me how I model the clothes. Once you have the body it's easier. For example, to create her shirt I first duplicated the body mesh and added a bit of push. Then I deleted all the parts I don't needed (legs, hands, head...) and tried to reduce the quantity of edges, trying to preserve the body's shape. It's just deleting edgeloops till you have it as simple as you can. Then I add the cloth parts, so for example, with the shirt, I added the seams on the lower part, where the body and the arms come together and all the neck zone, creating the shape and adding the rope. But still all as simple as you can, the less polys the better it will be. So I had something like in the image. Finally I added all the wrinkles. For me it's useful to have references even of an irregular think as the wrinkles, not to exactly copy them, but to have an idea of where will them appear and how. Creating them it's easy but boring for me. It's just selecting some edges you have (or creating new edges cutting them) and extruding them (with a 0 height) so you finish with a triple parallel edgeloop, and then you just have to move up or down the middle edges to create the wrinkle, move the vertexes to make it more irregular and weld target the vertexes on the ends of the wrinkle. And repeat this process with different shapes and directions till you're happy with the result.