How will I direct the scene in which Prospero forgives his enemies?
Good question. This scene has several key components for a director: the emotions, the interactions, and the physical blocking. These will intersect.
The emotional side of things will address the core reaction of each character to what's going on. For each of the characters, identify a core drive. Since Prospero is doing the forgiving, start there. Why does he change? Is he simply tired? Has he learned something? Is he overcome with love for his daughter? Let that core emotion drive and color his actions. Then repeat this with each of the other characters.
The character interaction will pivot both on these core emotions and on the reactions to specific lines. Prospero calls them "evil," after all. How does Alonso react? Review each of the statements for barbs and force, and imagine how you'd react if you were each character. Then guide the actors.
As for physical blocking, we've got an island, and you've got to have room for Caliban and the rest to come in—and for Prospero to cast his spells early in the scene. Show both ritual and trust through spacing.