My blogspot blog is 7 months old and is Page Rank 3. Now i want to change it to my .com domain. Will this be useful and will i regain my page rank in short future. Should i do it or not. Please guide me the proper way.
Changing the Domain name will not help you in regaining the page rank. As you said that your Blog is 7 months old. if you change the domain name you have start from the beginning again. hope that answers your question.
Changing blogspot blog to your own domain will surely hurt you. You will need to work another 7 months aging to get pr 3. I suggest not to move to new domain.
I made the mistake year ago of changing from a .biz to .com and my site disappeared from Google for 6 months. However, I didn't know what a 301 was and may not have done that.
As an example of 301 redirect: Site www . traindex . com were rebranded into www . etxcapital . co.uk and used 301 redirect. Their rating stayed intact and PR was passed to the new domain.
If you will manage to add page-to-page R301 redirection you most likely won't loose any traffic, rankings and PR.
Just make a 301 redirection. It's better to redirect old pages to new pages too, and to move the existing articles on the new site. At a 301 redirect 10% percents of total PR will be lost.