Selecting the topic
Ideas for topics come from myriad sources - some will be generated by interest in a particular area of previous work, others by discussing issues with peers and academics and some by reading the literature.  Initial ideas can also be in various stages of development - some will be vague, others clear and well defined and many will be in the middle of the two extremes.
Like a seed, most research ideas have an inherent potential for growth and development.
When thinking about a suitable topic it is important to consider the implications of your choice: