1. Bring donuts either at the start or end of visit. Just shows some extra thought.
2. Be mindful and thoughtful to the residents.
3. The more prep work you do, the best your questions (current peds trends, products, tx plan, etc)
4. It's essentially shadowing and wandering around the day and following the residents around
5. Talk to faculty when they are free
6. Be able to articulate what interests you about peds and why you want to do it
7. If this is a city you haven't been to, try to make the best of it. I did it with one of my externships and they were impressed with how much I embraced their town and explored.
*It's essentially a vibe check for a potential interview invite. The better the impression, the greater likelihood.