A colleague explained to me that it is a typographical rule to not set an indent for the first line of the very first paragraph of a text, the one that starts right after the headline. Instead, the indentation should start with the second paragraph. However, I am finding examples in various publications where the indentation starts right with the first paragraph. Then again, others do it the way it was told me.
Is there a "right" way to do it, and if so, why? If not, what are the advantages/disadvantages of either method?