In order to begin the process, have a think about your target audience, what do they look like, what are they interested in and what makes them tick. From there link your product or service to their needs and brainstorm what they might type into a search engine when looking to solve their problem. At this stage you want to ensure that the words relate to people who are seriously looking to buy, not simply browsing. It is all very well attracting many people to your site and gaining high click rates if you are not completing sales. For example if customers are typing in an exact product name they are likely to be buying at that point.
There are many tools to assist you to find popular search terms such as Google keywords tool and the wordtracker tool. If you type in your term it will tell you how popular that search term is. Clearly you want to ensure that your offer is going to be viewed by as many people as possible so it is critical that you get this right. The tools will also give you other keywords relating to your search which you could use.
Once you have a number of keywords you need to check how popular these terms are. You can do this by going into Google and typing them into the search bar. The number below the box shows how many sites have those keywords in them. If you have a number in the millions then it is unlikely you are going to able to compete in this space. Keep trying your terms until you find some with a number in the thousands as opposed to the millions.
The next stage is to see which sites are currently ranking on Google for those terms. If they are significant online organizations then it is less likely that you will be able to compete with them. At this stage you need to make a judgment call if you want to go ahead and target this keyword or move to something which poses less of a challenge.
As you can see targeted keyword research is not straightforward and it is easy to target the wrong keywords for your offer. But if you are prepared to put in the hard work you will soon see results. It is a case of trial and error and refining your searches until it becomes second nature.