Here are some of the important tips you can prefer.

1. Know the syllabus first , candidates who are very good in general mathematics, English and GK, especially the freshers. Always study the syllabus of cds exam which will help you to understand what they might ask in cds exam paper.
2. Refer to previous question papers of cds exam ; this method of preparation is followed by many successful candidates since many years.
3. Consider various preparation sources like books, e-books, online preparation, online groupds, blogs etc . This will make your preparation rock solid and you will also discover things which you are not aware of while preparing with the single source.
4. Start well in advance and make a plan as to how you are going to prepare for cds exam, stick to your plan till the end. Most of the candidates who are good enough to clear the cds exam never realize the importance of time, at the last minute they misses out the revising topics which are very important for cds exam, this leads to sure shot failure. So always try to kick start your cds exam preparation as soon as you can.

Use the books to prepare for the exam:

English

1. vocabulary- Norman Lewis
2. English Grammar- S.P. Bakshi

General Knowledge

1. Lucent
2. General Studies Manual by Arihant Publications.
3. Current Affairs from Internet.

Mathematics

1.Quantum CAT by sarvesh kumar verma