The following diagram shows the movement of Venus along its orbit in 2002. The perspective is looking down on the Solar System from above (North) and the position of Venus is marked at monthly intervals. All positions are relative to the Earth, which is positioned at the bottom of the picture.
By seeing where Venus is relative to the Earth, its position in the sky and appearance in the real pictures should make more sense. As it comes round the Sun so it gets nearer and therefore appears larger, but at the same time presents more of its dark side towards us, so the phase gets smaller. Hover the mouse over each real picture to see when it was taken. Note that they have all been orientated so the Sun shines from the right (as in the diagram), but if you click on them you will see that the originals show the inverted view as seen through a telescope.
Venus was on the far side of the Sun directly opposite the Earth (Superior Conjunction) on 14th January, when it would have appeared as full, though was too near the Sun to be seen. As it comes round towards us it will appear furthest from the Sun (Eastern Elongation) on 22nd August, at which time it will appear as half-phase (50%).
Maximum brightness will be achieved in the second half of September as the increase in apparent size of Venus offsets the diminishing phase. After this time, the phase diminishes rapidly until Venus passes between the Earth and the Sun (though not directly in front of it) on 31st October. Although it will be at its nearest to the Earth at this time, it will be impossible to see because the dark side will be fully towards us.
The diagram is based on one generated for 2 Jun 2002 by the interactive Solar System at the Jet Propulsion Laboratory's Liftoff website.