Hi Deepa,
The best way to prepare for certification is to download the tutorials from the IBM Site. This is a really great starting point.
Secondly create a login at
http://certify.torolab.ibm.com and start appearing for the sample tests. Though repititive they give you a really great idea of knowing where you stand in terms of the areas of questioning. Go on till you can score approx 80% consistently.
Once you are there, guess you can go ahead and give the exam.
This is the way I am prepraring.
Please also go through the useful stuff under the dbforums, that has links to online tutorials for 700
Best of luck
Regards
Nitin.