When starting to model using the box modeling technique the first step we want to take is having a side and front view of the object that is going to be modeled.

Setting these to be the image planes or the equal in other software packages, so that we can align the vertices to points within the image.

Once the images are lined up with each other I do almost all of my modeling within the two orthographic views, using the perspective view to use for tweaking the positions in the 3rd Dimension.

Once the eight vertices of a box have been placed at the far points of the torso I begin to add edges. Within Maya the Insert Edge Loop tool is the most useful at doing this. The key when adding more to the mesh is to do this equally. By not adding more horizontal edges than vertical we have an easier time to achieve realistic form.

Also once an edge is added in the proper thing to do is to adjust all of the vertices on that edge so that nothing remains where it was automatically placed when the edge was inserted. Also to make sure that all of the faces remain four sided this will help in every apsect of 3D, rendering, rigging, texturing, etc.

I continue this process of adding edges while looking at both the front and side views and then checking the perspective view. Once I have gotten far enough along I focus on creating edge loops that encircle areas of the form, such as arms, eyes, nose, etc.

By doing this the direction of the edge can be changed and more complex form and structure can then be modeled.

By following the form and using the edge loops the structure is developed, even rolls of flesh and muscle can be modeled, also it is modeled in a way that deformations will work and textures should not pull and stretch.

After all of my modeling is done, duplicate the other half over on the negative and merge the together. A smooth can then be added to see what is will look like for the render. Important thing to remember when modeling, good modelers model for form and structure bad modelers model for smooth. Smooth is just and additional accent and should not alter the models form, just slightly enhance it.

In my opinion this needs to learned first before jumping into higher end programs for sculpting such as Zbrush and Mudbox. If you cannot manually layout a good topology with correct edge loops and flow then you will not have the understanding of what is needed to make a rig work correctly with proper muscle structure.