Promoting products

Start by researching companies to find out which ones have product lines that might be complementary.

Never send an unsolicited proposal to a company. Their best response to avoid potential liability is to send it back to you un-reviewed. You must first contact them to find out who should get your proposal and in what form they might accept it.

Make sure your idea is protected with a confidentiality agreement, a patent disclosure and/or patent. This is for the benefit of all parties involved.

You'll need persistence. Sometimes the right person isn't interested, even if it is a good idea and would work for the company, because there's no compensation for new ideas. The corporate culture doesn't foster new ideas or they don't want potential liability from reviewing your idea in their business context.