This is a tough question. There are so many different possibilities as to what you can do if you want to start a business that you could do literally anything in the entire world. I definitely suggest finding something you are truly passionate about. There are always many opportunities to make money in every type of industry out there, whether it be health, food, sales, graphic design, and everything in between. It is more important to be happy with what you are doing than to make tons of money and be completely miserable.
That being said, within your desired industry, I suggest doing research on the types of businesses that are up-and-coming, or are very popular, in 2015. From this you can determine what the current trends are, what makes people happy, etc, and perhaps form your products or business around it. For example, if you are really passionate about selling/designing clothes, look into what types of clothing styles are "in" right now, and from there determine your target audience (men, women, children, etc) and take off from there!
Hope this helps!