The main thing to know is you'll come across trading cards as your collectibles and they're pretty fun to track down. Most show up early in jackson and during the seattle sections, with plenty stacked in the first few areas - keep an eye out for their playing card symbol which makes them easier to spot.

Getting all the cards will unlock the master set trophy, but if you just want to start small, grabbing five is enough for the starter set bronze. They're actually ellie's only collectible items since there aren't any coins to find this time around. You'll find most cards pretty naturally as you explore, but some need a bit more searching especially in those larger areas through the city.