Book subject: Junk collection
The story is essentially the same regardless of game. If any game offers you more abilities, connections, etc. and you have the capability of going most anywhere in the game's world, chances are high that there will be more optional things you can access this way. You could take notes on suspicious-looking places that would be worth a back-track as you play. This will certainly benefit you, but don't rely too heavily on it. What you thought was suspicious could just be some innocent thing that doesn't even offer junk as a prank, or it could be a leftover of some design that got scrapped. Similarly, if stuff is to be hidden, there will be instances where you're supposed to just gloss over them entirely, and only the slightest hint of anything strange will be offered. It is for these tidbits that you'll have to trek over the entire game world and spend much of your time micro-examining everything, while also looking for the familiar clues you've been taught along the way. Then there are those secrets which developers vindictively try to hide and give no hint whatsoever to locating them (case in point, search for the easter egg of Batman: Arkham Asylum).
As you can see, junk collection is very time-extensive and the rewards are usually very slight. Just know what you're getting into when you being such a quest. In almost every case, the experience will be like scrubbing floors with a toothbrush.