The backbone of any good search campaign is the keyword research, quite often after being entrenched in one industry you think that you know your market and you needn't research keywords again.
Having a solid list of trends and keywords from 3 years ago is not good enough, it's out of date. Sure, the big volume drivers won't have changed but those are the obvious keywords, in fact the big volume drivers of yesteryear are fading, people are becoming more savvy when they search. People don't want "blue widgets" anymore, they want "wireless blue widgets with voice recognition".
I have put together a few guidelines and tricks to use when doing your keyword research.
Know your industry, you think you can get away with synonyms in your options but the more research that you conduct into the business the more potential keywords you will get out.
Filter out anomalies and think about seasonal trends, make sure you can recognise the trends: in this search for the African big 5, we can see that the popularity of the leopard is waning, soon it will be lower than the other 4, not important you would think…
When you look at the real picture you realise that the wane is not for the majestic big cat leopards, but for apple fan-boys typing "leopard" into Google. Thankfully I don't have any clients in the windows business.
Use as many tools as possible. One of the biggest things that I have noticed from my research is that a lot of the different applications available use different data sets and depending on the source provide very different results. Certain toolbar data tends to give you a technological sway – while others will generally favour other demographics. A neat trick that I use a lot is to use Google Sets to make a few keywords into a lot to expand the research.
There are a load of tools available for keyword research, a lot of them are proprietary, but these all give you different results so they are good to have in the mix. The obvious choice for research always used to be overture, and more recently Google, their keyword generator is simple and free.
Be creative, with keyword research, it quite often seems like it is a lot of work to prove that the keywords you have are the best for your site. But the harder you work at it the more you see that there is always a better fit or a longer tail.