The affidavits people most often need
Nearly all of them are required by a third party (a bank, a school, a government office, an employer) and each has its own expectations about format.
What makes them get rejected
The commonest reasons are mechanical: the wrong stamp paper value, a verification clause that does not distinguish what is stated from personal knowledge and what from information believed to be true, missing details of the deponent, or attestation by an authority the receiving office does not accept.
Ask the authority requiring the affidavit what format they expect before drafting. It sounds obvious, and it saves more re-work than any other step.
Documents for use outside India
Notarisation alone is usually not enough for a foreign authority. Depending on the destination country, the document will need an apostille under the Hague Convention, or attestation by the Ministry of External Affairs and the relevant embassy.
For clients abroad, powers of attorney executed overseas have their own requirements before they can be used in India: including attestation at the Indian mission and adjudication of stamp duty after arrival. We handle those sequences regularly for NRI clients.