We have written posts about why selecting the right keywords is so important and also how long tail keywords can help you rank quickly because of the low competition. But another important factor is keyword search volume which means how popular a keyword is in search engines and how many people are looking for information typing in that keyword phrase in the search engines.
Targeting a keyword which you like but which has low keyword search volume will not take you far because there is absolutely not enough market for that keyword. So fewer people will be searching using that keyword and resultantly lower search engine traffic and it all comes to lower or no sales. Therefore you should always focus on keywords which have high search volume.
There are two types of keyword search volume in Google Keyword Planner. One is the local search volume and the other is global search volume. By global search volume we mean the total number of times the keyword is being searched through out the world and by local search volume we mean the number of times people are using the keyword to find information in a particular country.
Another important aspect of keyword search volume is that Google Keyword Planner gives it with a view to help advertisers on its Google Adwords platform by giving them an idea that how many people will be able to see their ad for a particular keyword. There are other keyword research tools too that give a different data based on their own software and reach. But still personally I still consider the data from Google Adwords keyword tool to be more reliable than other tools, given the dominant position Google enjoys in search engine market.
More importantly, when selecting a main keyword for your website, never use one with a keyword search volume of lower than 2000 monthly local searches with the geographical setting set to United States in the keyword planner. Because anything lower than that will not be making a lot of business sense.
If you are making an information website for the global readership, then using the metric of Global keyword search volume should be used.