Hey Mugdhab - that's a pretty general question! But I'll take a stab. What you want to do is LEARN and keep on LEARNING. You need to learn about QA practices, whatever technology you're working with and about the software you're testing itself. To start, you probably want to get a good book that focuses generally on testing. My personal fave is Testing Computer Software by Cem Kaner et. al. Also, read www.softwareqatest.com in its entirety. Try to absorb as much information as you can. Then head on over to www.stickyminds.com and read the articles there. When you've read the information and you've got specific questions, come on back to qaforums, do a search to see if that question has been answered and if not, post it. You'll find that once you have a good base knowledge of QA you can get into some pretty interesting discussions with forum members here.
Good luck in your endeavours!