Are you asking the correct question? Your clients are.
To get to the front page of Google or any search engine you need to make sure that when people find you it is because they were looking for you and not something else (this is obvious) but sometime you will think that the keywords you are using and the phrasing that you understand as a expert in your industry is the same language that everyone else is using.
Unfortunately this is not the case. Your customers are speaking your language but what about the people who are not your customers, are they speaking your language?
If they are not your customer then not. This is very important for internet marketing and effective SEO keyword research.
To get to the correct keyword research there are a couple of key questions that you need to ask yourself and the client.
First make sure that when you create your sales pitch it is not filled with the same jargon that you currently have on your site as this defeats the point of finding new customers.
Then look into other industries that offer similar products and services but you don’t consider to be Competition. This will give you some insight into areas that you have not considered and you can then add some keywords to your research.
Remember you need to align your Keyword research with this year’s goals of the company.
If you are focused on short term gains you will need to focus on PPC if you are looking to increase please and revenue overall then SEO will work better.