I personally would start at looking at what your passionate or enthusiastic about. When you are really committed to an idea you will have no problem putting in the extra time and energy to make it work each and every day. Grant-it you need a good niche and there MUST be some type of market already in exsitance to add to your bottom line; not to say that no market means no money, just that its much more work to get people to buy into at first without a GREAT slaes pich.
Do your research and look at what your abilities are, what resources you have or could get over the next year or so.
"You Only Fail If You Quite"