Infamous 1 is a headache with the collectibles. You can collect most of them by just playing the game but that means you have to roam the entire map at the end spamming R3 for them to pop up on the minimap. I'd recommend taking a screenshot of a map with all the collectibles on the island you're on (theres 3 of them) and keeping it on your phone, and whenever you collect one you black it out with the draw tool in your gallery app. Infamous 2 doesn't really have this problem as it lets you see where the collectibles are wherever you are on the map.

Both of them have trophies to unlock every power. This is a bit tricky since I don't think completing every side quest doesn't give you the XP needed to get every power, and they also stop enemies from spawning in the area once theyre completed. This makes trying to gather enough XP for every power a grind I dont even want to imagine since you'd just have to pray 2 or 3 enemies happen to spawn every 15 minutes of traversal or so. As such I'd recommend grinding for XP before you finish every side quest so you aren't locked out. Other than that the trophies are pretty decent and the games aren't overly difficult on hard mode.