Buy the stamp paper of requite value as per stamp act of the state, in which the document is executed in India.
Type out the power of attorney and present it to the sub registrar where either the principal is staying temporarily or if both are at the same place to the jurisdictional sub registrar of the place. Pay the fees prescribed and get registered.
Note 1; The language of the POA should be clear and unambiguous. Don't use American drafts, since most of them are wide in scope and vague.
2. In India, POA is not compulsorily registrable. Paying stamp duty is sufficient. you can get the same notarized with a Notary Public. Care should be taken to get the same entered in the notary register and the serial number is duly recorded on the document with approciate seals. This is cost and time effective.
3. If the POA gives power to sell a landed property, then registration is compulsory, and better to register it at the sub registrar's office having jurisdiction over the place where the property is situated.