My first thought was spanish or chinese language teacher but seriously I expect the world will finally start to embrace some of these "alternative energy" schemes so that may be a growth industry.
The fact remains you can probably make a good living as an employee but you won't get rich until you work for yourself. That requires more business sense than trade skill. It also requires a lot more work and a whole lot more risk. Yoiu should never stop learning. The world is a dynamic place and things are always changing. This doesn't have to be college, you can learn a lot while you are working and the internet is a great source.
