Omar, that's a loaded question. and probably too much to answer on here. Your best bet is to go to google adwords and use their keyword tool. you can look up different keywords and get information on them. There is quite a bit involved with keyword research that can't be explained briefly. I don't know if I am allowed to do this since i am still a peon, but I have a free report available on my website. www bearworksonline com. look on the right side under "free reports."
your website topic is usually somewhat related to its domain name, otherwise it is somewhat related to your interests and the topics you are interested in writing about you won't be able to make it work if your only driver is $25/click keyword that is insanely spammed and have no other appeal to you whatsoever
You can take help from google adwords.It will help you to select effective keyword.At this moment I prefer forex signal keyword.