In this talk, I will take tetragonal and rhombohedral mixed-phase BiFeO¬3 as an example to share with you about our investigating steps and thinking process when dealing with a new research problem. Ferroelectricity, magnetism and the electrical control of magnetization are of particular interest in emergent state of the material. In order to look deep into those properties, a combination of scanning probe microscopy (SPM) and x-ray absorption based techniques (including x-ray absorption spectroscopy (XAS), x-ray circular/linear dichroism (XCD/XLD) analysis, photo-emission electron microscopy (PEEM), etc.) has been employed. This talk will focus on the study process of how we first understand the ferroelectric and magnetic properties separately and then combining all the knowledge and tools to finally realise a deterministic electric control of magnetism in this system.