Step 1
In a new file, select all the objects with the A key and then press Del to delete them.
The first step will be to add the background image for reference. With your mouse in the 3D view, hit N on the keyboard to bring out the Properties panel. Scroll down to the Background image panel and clik on 'Add Image'. Click Open and browse to select your image. The Background image is only viewable in 'Ortho' mode in the Left, Right, Top, Bottom, Front and Back views.
Step 2
Now we will start the character with the leg. Press Shift+A and add a Cylinder. In the Tool Shelf, reduce the vertices of the cylinder to 8 and the Cap fills to Nothing. We are making a low poly character so a cylinder with 8 vertices will be perfect. Press T the toggle Tool Shelf on/off.
Step 3
Press 1 on the Numpad to get into the front view. Then Press 5 to switch to ortho view, move the object to the center of the character so that we can get the center point of the cylinder (marked with the orange dot) at the center of the character. Select the object by Right-clicking and press G to grab, then move the mouse to move the object and Left click to confirm.
Now align the object from the side view as well. Press 3 on the numpad to get into the Right View. Select the cylinder with right click, press G and move the object. You can also use the widgets to move.
If you want, you can also split the 3D view into two, by dragging the top corner of the 3D window.
In the left 3D view, press 3 on the Numpad and set this as the Right view. You can skip this step if you prefer one view and only toggle it when necessary.
Step 4
In the Front view with the cylinder selected, press TAB to enter into Edit mode. Select all the vertices with the A key, and press G to move them to the ankle. We moved the cylinder in Edit mode because by doing this, we keep the object center (the orange dot) intact.
Step 5
With all the vertices selected, Press S to scale the Cylinder down to match the reference. Check from the side view also.
Step 6
In the Properties window, click on the Modifiers button and add a Mirror Modifier. This will automatically generate the mirrored symmetry on the other side of the object center.
Check the Clipping option. This will make the center vertices 'sticky'.
Step 7
Now we'll advance with the modeling. Select the top row of vertices using Alt-Right Click (you can also Drag Select with the B key.) Press Z to enable transparency so that you also select the vertices behind.
Press E to extrude the mesh and Left-click to confirm the position. The new row should be at the middle of the knee. Press S to scale to match the reference.
Step 8
Extrude again to the tip of the knee, and Scale to match the reference.
In the Side view (press 3 in the Numpad for the Right view), match the new edge loops with the reference. Select the edge loop using Alt+Right click, and move them with the G key. Scale accordingly Remember to scale ONLY in the Y-Axis as we already Scale-Matched in the Font view, so we don't want to disturb that. Press S and then Y to scale only in the Y-Axis.
Step 9
With this Extrude and Scale method, build up the leg of the character. At the end, Rotate the last Edge Loop with the R key. Remember to Save your file frequently with Ctrl+S.
Step 10
Check the mesh in the Side view as well. Remember while matching the loops with the Scale command, Scale only in the Y-Axis.
Step 11
Hold down the Shift Key and Right-Click on the middle five vertices to select them. Press E to Extrude them to the middle. As we had clipping ON in the Mirror Modifier, they will stick together.
Step 12
Select the top edge loop. Alt+Right-Click on the edge to select the complete loop. Press E to start extruding the body.
With the new row selected and in the Front view. Press S and then Z to scale the loop in the Z-Axis, so that the vertices are almost aligned in a line. Adjust the bottom vertices as well.
Step 13
Adjust the vertices of the newly formed loop to give it a nice round contour.
Step 14
Select the top edge loop and Extrude once more to form the waist line. Scale down the new edge loop in the Z-Axis to align them, and Move and Rotate to match the reference.
Step 15
Tweak the vertices in the side view to match the reference. You can select the whole edge loop using Alt+Right-Click, and then Scale them up in the Y-Axis.