Hey Tejas,
I just wanted to know if I got you right. You mean sourcing profiles from the job portals rite? Now that comes with a bit of practise. And when you keep doing it you will know the basics. Whatever your search mandate be, try breaking it in to small parts. Like if you need someone for Event Management then you need to think about "Direct marketing", "Roadshows", Interactive marketing!! the reason is because these search mandates will only work the way the candidates have put their search nodes! You need to think from their shoes and then try hitting the right search word. Otherwise what will happen is If i search for event management then the site would throw me profiles containing C, C++ :-)
I hope you got a bit of an idea..
take care pal,
Sunil