Next is the torso

For the torso, we'll do it a little different. Instead of unwrapping and then adding symmetry on top, we'll unwrap the whole torso already mirrored. So you can right-click on the symmetry modifier and collapse all right now.

It's a lot easier to hide symmetrical textures on the legs or shoes then it is to hide them on the front of a shirt. Perfectly symmetrical cloth wrinkles on a shirt front often look bad, so we're only going to mirror portions of the texture.

Start out by putting an Unwrap UVW modifier on the toros, expand the + sign so you can select Face, select the entire model and click the Cylindrical button. Move and Scale the gizmo so that it fits the torso as best as possible.

Next change to Verticies select mode, and click the Edit button.

My plan is to mirror the sides and the back, but leave the front as it is. First I selected half the back, detached it (Ctrl+D) and then Flipped it horizontally and moved it over top of the other half of the back.

Next I selected the half of the side on the right that I wanted to share UVs with the other half. I Detached them (Ctrl+D) Flipped them horizontally, and moved them over to the portion of the other side that matched them.

There was one more thing I needed to tweak on it before I could consider it done. The faces that make up the shoulder are very small in the UV unwrap because they're at an angle from where the projection was coming from, so they're very stretched in comparrison to the rest. So I selected the verts of the collar and pulled them upwards to increase the length of the UVs for the shoulders.

Once I'm satisfied with the unwrap I fit it into the square, render a UV image, save it, close the edit window, and right-click on the Unwrap UVW modifier and choose Collapse All.