Just another note to help you - try to find out what you really enjoy. I really enjoy reading about debt (even though its not a area I want to go into). From that I loved reading about 'niche' (in a sense of people who arnt interested in financial markets at all) areas of finance like repo markets. I've read far to much into this but I find it fascinating to know how the economy functions and how the US was so close to a disaster. I've noticed this works really well in interviews as if you speak about a area they may questions you etc but if you show you know about it by adding in little bits of information thats beyond a news story, like a academic article. You can find these as many news sites will cite from these articles and provide links, thats how I found out about the different types of repo markets and how each one functions.
Do you have anyone to discuss news with? I'm fortunate my dad keeps up all the time with news so I challenge myself to know more than him (which is impossible) but we discuss recent stories and this just helps to get someone elses opinions, as well as different political opinions on stories. This is very important as it can help you debate a story. If your in a AC and your interviewer casts doubt over something, dont just fold instantly becuase they may just be trying to push you. Unless you are very clearly wrong stick with what you think is right but acknowledge and build on their comments, its fine to change stance, but only do that if you have gone wrong or you have overlooked something in the news you read. It may also be good to state that in this particular instance you have got it wrong.