A tool for keywords:
1 Find an online text. Read it and make a note of what you think the keywords are.
2 Copy the text. Click on this link
http://www.usingenglish.com/resources/text-statistics.php and paste it. Press the Calculate Now button.
3 Look at the results. It removes common grammatical words and shows you a Word Cloud, where the bigger the word is, the more common it is in the text. This often shows you a clear picture of the most important words relating to the theme of the text. It works better with texts that are a couple of hundred words or longer.