The easiest way is to be in an industry. When you understand a set of products and the commercial drivers - the state of the art, you can start to try and ident

The easiest way is to be in an industry. When you understand a set of products and the commercial drivers - the state of the art, you can start to try and identify inefficiencies and gaps. You can see where big companies are skirting around problems they don't consider profitable enough to be worth tackling. Obviously you can't work in and deeply know every industry, so maybe the answer is to go to trade shows and contemplate what products and services people are offering and try to sniff out opportunities or ideas to investigate. It'll help that you'll have SMEs on hand at such venues.