How to choose a topic for decorating a room?

The internal situation of the premises is based on a certain topic and concept that determines the nature of the space or house as a whole. How did you choose the existing interior? If it contains disparate details and general ideas are not thought out, then you most likely did it wrong. So that you like your home, you must invest in it a particle of yourself and your own thoughts. How to do it and where to find inspiration?