Well there's another way that I feel works best for those who can think ahead. It has to do with knowing your industry or niche really REALLY well. Like seriously...you know the pulse of the industry and you know what things are to come. And the moment you start to notice new products, or product categories, or industry jargon, you capitalize on that be being the first one to use those [not-yet-common] keywords.
This is what I do to stay several steps ahead of my competition. By the time they catch on to it, my site outranks them easily because I've had the keyword on my site for a long time before theirs.
But it's more than just SEO. It's about really knowing your shit and like I said...REALLY KNOWING YOUR INDUSTRY. It's just about knowing the latest keywords. It's about knowing the latest concerns, things that TODAY'S customer cares about, what people are talking about. And if you don't even know these things...then is your business truly qualified to even succeed?