If you want to determine if the moon is Waxing (getting bigger) or Waning (getting smaller) all you have to do is look when you can see it. If it is visible in the evening sky the Moon is Waxing (getting bigger). If the moon is visible at dawn or in the early morning, it is Waning. Here is a rhyme to help you remember it:

If you see the Moon at the end of the day
A bright Full Moon is on its way
If you see the Moon in the early dawn
Look real quick, it will soon be gone.

Another way to identify a Waxing or Waning Moon is to look at which side is "incomplete". When the Moon is illuminated in such a way that the side facing West is "incomplete" the Moon is Waning (getting smaller). It the side to the East is "incomplete" the Moon is Waxing (getting bigger)