My plan is for the shirt and pants to be seperate meshes. The jacket is very baggy and extends over the pants a lot, so the two objects will not connect directly. Because of this, I need some of the pant geometry to continue up under the jacket. This is especially important for when the character is rigged and animated. It's important that a big empty gap shouldn't appear under the jacket.

Shape the edges in the front viewport to match the legs better. It is ideal to have a V-shpe coming from the groin area. It will deform a lot better if you do this.

For the Groin area, I selected the inner edges, held down Shift and moved them to the side to extrude new faces. Then I selected the bottom verts (circled in image) and clicked the REMOVE button. The remaining verts need to be moved to the exact center. Select a single vert and at the bottom of the max window under the animation timeline are three areas where you can enter numbers. Change the X axis location of the vert to 0. This will move the vert to the center. Do this for all of the verts you have here in the center of the groin.

Switch to the Perspective viewport and start tweaking and fixing all of the the shape problems that are bound to be there. If any side looks really flat, just bring in the edges more to round it out some. You also need to attend to the butt. This area will require some cutting and a lot of small adjustments to get it to look okay. In this model isn't not a huge deal if it looks perfect since it will be mostly covered by the jacket, but it's still a good idea to get the geometry fairly clean on it.

Chances are that the leg is very faceted at this point, so lets do the smoothing groups thing again to smooth out our leg. Go to Polygon select mode and select the whole pant leg and set it to smoothing group 4. Rotate around the leg and clean up any problems you can see with the mesh.

Now it's time for Symmetry.

Go to the Heiarchy tab. Closer to the bottom are these two buttons. Click them both.

Now at the top there is a button that says Affect Pivot Only. Click that button. The move cursor will change a little to show that now you are controlling the pivot. In the X Axis entry at the bottom of the screen, set it to 0. Now the model's Pivot is in the exact center.

Return to the Modify tab and click on the drop-down menu that says "Modifier List".

Scroll way down towards the bottom and find the modifier called Symmetry. If you're model suddenly disapears check "Flip". If it's doing symmetry from the wrong directly, toggle through the Mirror Axis until you get the right one.

Now is a good time to go and fix any screaming errors that only now make themselves apparant. You can go back to the Editable Poly and continue working on the model with the symmetry modifier on the top of the stack. But when you go back to editable poly, suddenly you won't have the symmetry anymore! But we can fix that! There is a set of icons directly under Editable Poly, but above the parameters. The 2nd button is "show end result". If you click this button, it will show the symmetry, even when working in the Editable Poly area.