Circling is good advice, if you have to get down on all fours looking for blood along the path the deer took.

Some states have dogs who will blood track and this service is often free might be worth checking out http://www.unitedbloodtrackers.org/index.php
They will want as much info as possible about where you hit the deer and what sort of penetration you got also how the deer reacted to the shot.

Good luck