There are a number of different customs as to how to wrap the tefillin Strap on your hand. In my minyan I see at least seven different traditions. We should use the custom that our fathers used.

     This is the tradition I use. I like it because the way the strap is placed on your hand spells one of Hashem's names.

     Do you see the name? The strap on the back of the hand is placed in the shape of the letter Shin ש, the next three wraps of the strap on the middle finger and the lower finger form a Dalet ד, and the last wrap on the middle finger forms the letter yud  י  Shin Dalet Yod- the Almighty.