The first consideration are the tags of your title.Because you open a first page via the web browser, the tag of title appears on the top of the first page as usual.
This is only depends upon the marketing product that which type of the product you are trying to introduced in the online maket and the keywords are also based upon them for the right selection.
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Experience about flatulence cure
I use the google analytic tool when i look at which keywords i want to target (because you can see how many times each keyword is searched.ect, so you can see whether there is any point trying to aim for it)
Choosing a right keyword is very important and it is depends on what product/services you offer in your site. for this You can use Google keyword tool for your help.