I doubt there's any canon description.
For myself, I'd probably assign different nationalities different salutes based upon their real-world inspiration.
American style (palm down, index and middle finger touching the brim of the hat) salute for Andoran.
British style (palm out, index and middle finger touching the bring of the hat) for Cheliax-sphere countries.
Maybe a "Roman" fist to heart salute for Taldor? I dunno.