You can get some hints in the notebook.
Look at the license plate on the car.
To get the valve handle on the rafter, push the chain.
In the museum, left of the statue, you can go in the door to get to the gift shop.
When you get to the frozen guy by the blacksmith statue, you can move the outer tiles with the symbols.
When you get the fallen beam, you can use it to cross the room with the large gap in the floor.
When you get the glass vial you need to put some mercury in it.
To solve the puzzle at the ruins, click on the crime computer.