I have done some internships related to business development & marketing, here are some of my thoughts:
1. business development is very strategic position and it requires a lot of experiences/ research into the market. You have to know every aspect about the business, watch your competitors daily and be alert what is happening in the space you are competing. On top of that, you need to think "what's next" every minute as it affects where the business goes. In a nutshell, you will be the one deciding : the competitive advantages (and how to maintain), differentiation, etc... not easy to do and u will learn a lot along the way...

2. marketing is not a " Qing chun Fan"; Brilliant marketing compaigns is a holistic project around the whole brand image. just look at how Apple works, their colors, their ideas ( haha ,my all time favorite...); Those are not easy... and it does require a DEEP understanding of the market (consumer behavior,who you are trying to target, why are they buying into your ads, etc)and how the system works ( eg. in Singapore,which companies you should go to if you want to put a bus ad and what their costs are); Obviously, your analytical skills are crucial in decision making in the area.

:-)

Hope you will like the industry and like what you are doing; :-)

[cannot type chinese on school computer... getting tired now... ] FYP is going to kill me...