Steps to follow:
1. Obtain the UAE Form online and print it out, fill it.
2. Obtain your fingerprints on a fingerprint card from your nearest police station.
3. Get this fingerprint card attested by the Ministry of Foreign Affairs (India)and also by the UAE Embassy in India.
4. Send the relevant documents (Copies of UAE Visa, Emirates ID, Passport, etc.) to UAE and obtain the PCC from Ministry of Interior, UAE.
If you have already received ITA, then certainly your best option is to go via an agent. The agent should charge you around 30k to 35k INR. Agent should do the attestation part for you as well since it has to be done from New Delhi.
One such agent is "Genius Group". I obtained my UAE PCC through them when I was in some different country last year. They handed over the UAE PCC to me within 15 days. You pay the money only after you obtain the UAE PCC.
http://www.policeclearancecertificate.info/contact-2.php
All the best.