Some of the best designers I know are curious about every thing in their environment both natural or man made. So much so that it annoys the non-designer people around them. Imaging having to stop and look at the way a stop sign is connected to a sign post often annoys significant others.
This curiosity feeds your mental dictionary of things, doo-dads and what-nots. By understanding how everything around you works, how people or companies make things, you can be easily inspired to create the next fantastic design as this information will be at your finger tips.
As they say there are no real original designs just innovative interpretations of designs put under different circumstances.
I really like to look at how the insides of things work, also not to only look but to understand how they manufacture it. If there are plastic parts look for cavity markings, flow marks, sink marks, wall thickness relationships, draft angles, ejector marks and gating points. For metal parts look at the folding techniques, the mounting points and edge detailing. Also dont forget to see how internal PCB mountings are done as well.
Remember not to “look” but “see”.
Check back with yourself in a few years you will be surprised by how much you will have learn if you keep your curiosity radar on all the time.