In the Top View select the edges along the heel and toe and repeat. Now you've made a division down the center of the side and top of the foot. From the top now select the sides of the foot and click the button next to connect, this time we want 2 segments.
Go back to vertex mode now and start moving things around in the different viewports so it matches the shape of the foot. Switch between the side and top viewports to get the shape better. For the part of the foot where it starts coming up in the front, I select the edges along the top of the foot, but not the bottom and hit connect (only 1 segment) then connected the edge verts to one of the near verts to avoid n-gons.
Go to the Perspective Viewport now and take a look at the foot. Obviously it's not going to be quite right, but it's closer. Start bringing in areas like the top of the shoe, around the heel, etc.
The temptation will be to start adding more geometry so you can match the shape better, but TRY NOT TO. You will add detail with the texture. Think of this as a big lump of clay and you're just aiming to get the general mass and shape of the object. Try to achieve the best shape you can with as little geometry as possible. There's no point wasting a bunch of verts on the feet when you've got a tight budget.
But Some new geometry is sometimes necessary... I decided that I wanted to define the heel of the shoe, so I selected the edges circled above and clicked connect with the box. Change segments to 2 and adjust the values of Slide and Pinch so that it's closer to the actual heel. Then select one row of verts and pull them up.
Make sure to connect the new verts to other verts to avoid n-gons. Tris (3-sided polys) are okay, Quads (4-sided polys) are okay, but not 5 or more.
Check all the various angles frequently to judge if you're getting the volume and shape right.
3D Studio Max uses smoothing groups to make low-poly geometry look smooth. In Real-time it's called "Normal Smoothing". Most all 3D apps have the feature, but each call it something different. (In Maya it's just Hard or Soft Edges for example)
To control the smoothing groups you have to be in Polygon select mode. Select a group of polys (or your entire mesh if you want) and scroll down in the Polygon modifying area until you see the Polygon Properties rollout.
The smoothing groups area looks like a grid of numbers. Each number is a group that will be smoothed together. If you select a group of polys and you see several numbers grayed out that means that these polys do not all share the same groups.
For the foot, first select all of the polys and click the Clear All button. The model will now look completely faceted.
Now select just the heel, and the ball of the shoe (but not the indent) and click the 1 button.
Now select just the indent and click the 2 button.
Now select the rest of the shoe and click the 3 button.
You've now assigned smoothing groups.The shoes are one of the few areas will I will separate out areas for groups. For most of the model, I will have the entire mesh all be assigned to a single smoothing group.
Once you're satisfied with the shape of the shoe, select the polys that make up the top border and delete them. Then go to Border select mode and click on the open edge.
Now go to the Left viewport, HOLD DOWN SHIFT and MOVE the edges up. Instead of moving them, it has created new polys!
Do this a few more times, going up the lege to around the knee. Remember, the fewer edges you need to get the correct shape, the better. We're just working the left viewport right now, we will move to the front viewport in a moment but first, lets add in a few small details.
A lot of people feel like they need to add in an entire row of edges for every little detail, but that's a waste. We want a little bit of geometry for the major wrinkles near the bottom of the pant leg, but don't need an entire row of edges for it. Select the front edges and click connect and adjust the slide so that the new edges are lower. Connect the edge verts to an existing vert to avoid n-gons. Move the new verts outward to closer fit the contour of the leg.
Go ahead and do this around the knee area as well. Once you've got the side going up just past the knee and are happy with the basic shape, switch to the front view.