I will recommend you to use Google Adwords and your brain. Google Adwords has everything what you need. Also there is few sites and tools that can help you while you will research keywords.
1. Your brain (the most important "tool" you will ever need) - free
2. GKT (Google Keyword Tool) - free
3. Ahrefs/Majestic/Moz for competition research - start with Moz for free (using 4 months trial coupons) and once you make money move to the other 2.
how to perform keyword research? any guide for newbies?
May I know Which tool you have decided to use?wow, thanks everyone for your help. i really appreciate it bros... thanks again everyone. happy earning to us