Invited talks are important for moving up the academic ladder, so I'd like to know how does one maximize the odds of being offered to be an invited speaker at the conferences.
I am aware of the most obvious things like having important results to report. However, apparently this is not always necessary: one often sees in the list of invited speakers some fresh PhDs neighboring the really big shots. So, are there any non-obvious strategies to increase the odds of becoming an invited speaker at a conference?
I realize that the advice may be field-specific, and I am most interested in the tips for conferences in mathematics and physics.