James Potter pondered about why he was here and how to get to his son. He thought back to what he learnt in Defence Against the Dark Arts when you find yourself in a random place.
Check for immediate danger. James scanned the area around him and found nothing hostile.
Look for familiar signs. James noticed he was at the edge of the forbidden forest at Hogwarts. In the distance he could see the twinkling lights inside the castle.
Figure out how to get around unnoticed if need be. James remembered the invisibility cloak
"I, James Potter, descendant of Ignotus Peverell command that the cloak of invisibility return to me in my time of need."
With this the cloak shimmered into existence in his hands. Swishing the cloak over his body he decided to pay Dumbledore a visit.