Watch a few episodes of Dragon's Den and observe what the pros look out for in new ideas/inventions.

I noticed the first thing they consider is how fast can they get a return on investment, how big is the market, is there competition, is the idea/concept solid, is the "first impression" about the product positive, does the product already have a customer base, what is the potential growth, does the inventor know what he is talking about, etc.

http://www.cbc.ca/dragonsden/