Wait, the user specified "best"—so the essay needs to argue that the PDF is the best option, not just a good one. Maybe compare it with physical books and other digital formats. Stress the immediacy of download, no shipping, easier updates for content corrections, etc.
The dialogues are scripted, but you need to make them yours. After reading a dialogue between Marco and Lucia about what they eat for breakfast, close the book. Stand in your kitchen. Pretend you are Marco. Say the lines out loud. Then pretend you are Lucia. It feels silly, but it builds the muscle memory in your mouth for Italian pronunciation.
Nuovo Espresso does a great job of presenting grammar in small chunks (usually in the yellow/colored boxes). Do not obsess over memorizing every conjugation perfectly before moving on. Use the grammar box to understand why a sentence is constructed that way, do the exercises, and move on. Perfection is the enemy of progress.