Choosing the best keywords related to the subject of the blog post helps the blogger to target the related keywords and get maximum possible organic traffic coming from search engines. Doing keyword research using Google Keyword Planner tools also helps you in getting an estimate of traffic/search queries for a particular keyword in Google.
There are various tools available online which can help a person in doing keyword research. A quick search on Google will yield you some popular keyword research tolls, some of which are free whereas some are paid.
I would suggest every blogger and webmasters to do proper keyword research while starting their own blog or website and also while writing individual blog posts so that they can target proper keywords and get maximum traffic to the blog.
"Winners don't do different things, they just do things differently"