As a student or as someone who has recently graduated, how would you decide which domain you are inclined towards and then decide to pursue a career in it?

I have met quite a few students and recently graduated freshers who have had good grades and a sound technical knowledge, but are clueless about the domain that they want to pursue a career in. Having a plethora of options to chose from only makes this decision making process harder for them.

So my question is, what advice would you give to someone who is just about to step into the real world and has no clue as to what domain he is interested in?