For sale of properties, execute a Special Power of Attorney, wherein you mention specifically all the details of the property to be sold including the flow of title to the current owner. Mention clearly that the POA is given without any consideration on part of the Attorney holder or else now STAMP DUTY is payable as per market value of the property, on the POA. If POA is given to blood relatives, then stamp duty amount is Rs. 500.
In your case the power of attorney should be executed on a plain paper. No need to use a stamp paper. Ensure that you sign in front of the consul officer, put your left thumb impression and affix your photo, which is then stamped by the consular stamp and then the consul officer signs it. There should be a place where your wife/mother/father/brother is going to be sign, put Left thumb impression and his photo. This page should be left blank as your wife/mother/father/brother cannot sign before you have signed.
Once that is done, send the POA to india and have it adjudicated by the local stamp authority, who will affix the required stamps on it. The POA is then ready to be signed by your wife/mother/father/brother, after the adjudication is done.
Almost all financial institution insists on POA executed by NRI's to be compulsorily registered. In most of the states in India, POA's for sale powers have to be registered, not notarised. So it will make sense for you to register the POA.
This is currently the correct procedure as per the latest amendments in the Stamp Duty law n registration rules. People do manage to use notarised POA to save time and money, but that is not the correct procedure.
Please note that it is NOW mandatory to have the POA registered specifically for property matters.