In pre-order traversal, the root node is visited first, followed by the left node and then the right node. The principles of pre-order traversal are as follows:

1. Display the data part of the root (or current node).
2. Traverse the left subtree by recursively calling the pre-order function.
3. Traverse the right subtree by recursively calling the pre-order function.

The preceding tree will have F, B, A, D, C, E, G, I, and H as output as it is being traversed in pre-order.