NLT Media games are very linear and so if you play them out of sequence, not following the logic and timeline of the game, you often end up reaching a point where some expected event fails to happen because you missed out doing something before you got there. The flow of the game is like a train on tracks and needs to be obeyed to ensure easy success. Best thing to do is to proceed, guided by Arianna, following the flow of the game and you should be fine. There's not that many locations to explore and these days several non-playable characters are there to offer hints and tips if you "speak" to them, e.g., suited and booted man near front desk of police station who tells you that there's a key in the "church" grounds which can only be found with a metal detector, informing you at a stroke you where to look for a key and what tool you need to do so. And where in North Santiva could you purchase a metal detector or possibly parts to make one? First point of call would be a public shop of course!
NLT Media games have a certain style and once you grasp that playing them really isn't difficult.
Point is that wandering about randomly and doing things out of sequence can spoil the game, because if you miss some action or interaction with characters at particular points, sometimes you won't be able to go back and do whatever it is that allows you to complete the game completely later. Best policy is to make saves of the game as you go so if you fuck up you can go back and pick up play before you jumped off the tracks. If worst come to worst and you really are having trouble completing a particular chapter simply wait until somebody produces a walkthrough for you and replay that chapter from scratch following a successful path discovered by some other player.