I think you need to look at Vinny's post, which was the first response. He had some good points.
What interests you? What do you look forward to doing?
There is not a simple answer to this question. For you to enjoy and become really successful with any business, you have to have a passion for it.
I started my own retail store a few months ago. I specialize in remanufactured ink and toner cartridges for your printer. Now I'm not a treehugger, but I've always been interested in saving the enviroment and I've too have always wanted to start my own business.
So I searched and searched for a business that I could start that I found interesting.
Things are going pretty good for me, and there are a bunch of opportunities that have been coming up because of me wanting to learn more about the business and industry.
So do some homework, and think about what really interests you, then if you can narrow it down to a couple of things, try to think of how you can make a business of it.
That would be a good question to ask everyone for their opinion on. Example...I'm really interested in working with animals. That will give everyone here a starting point to suggest things to you.