Since the Jacket is going to be a seperate object, I'm not just going to extrude it from the pants like I did the pants from the shoes. But I don't want to start from a box either. So I selected the edges along the top of the pants and held down SHIFT and pulled up to create a new row of polys. I went into Polygon edit mode, selected the new row and clicked the DETACH button.

At this point you will still have the legs selected. Deselect the legs and select the new detached object you just created. Go into vertex mode and start moving the vets so that it matches the reference. Also check the side view to adjust for that as well.

Select the edges along the top and use the Shift+Move technique to create new sets of faces. Make sure the center verts stay at x:0 so that the shirt won't end up with holes in it when you apply symmetry to it.

When you go into perspective view you'll probably see some problems - certain parts may not have enough edges and others may have too many. To remove a row of edges first select the edges and click the remove button, but THEN you need to go to vert select mode and remove the left over verts that used to make up the edges. Just select any isolated verts and click the remove button.

To add in new rows of edges, just select the edges edges you want to make a new edge between and click the connect button.

Instead of just continuing upwards, at this point I decided to get the neck setup so that I could build between the two.

I went into polygon select mode, selected the top row of polys and held down SHIFT and moved them up towards the neck.

Instead of extruding new polys, like what happens when you hold shift on edges, this simply makes an exact copy of the polys you had selected.

I adjusted the verts so they lined up in the front and side viewports and then went into perspective view and cleaned up their locations.

In addition to basic clean-up, I also removed a few edges (remember when you remove an edge, you also need to go in and remove the verts too). The amount of edges that were present lower in the torso weren't nessecary for the collar.

At this point I did two things to help me continue working. I applied symmetry so I could judge the total mass better, and I applied smoothing groups so that it wouldn't be faceted anymore. Just do it the exact same way we did above (For smoothing, just select all of the polys and pick a smoothing group number; for symmetry click on the Modifier List drop-down and scroll towards the bottom where it says Symmetry).