Making a call to a DX station requires a little more attention to the clarity of your speech and sending than making a call to a nearby ham. Your signal likely has the same qualities as the DX station, hollow or fluttery and weak, so speak and send extra carefully. Give the DX station call sign using same phonetics they using and then repeat yours at least twice, using standard phonetics. On morse code contacts, send the DX station call sign once and your call sign two or three times at a speed matching that of the DX station.
Dx contacts, except when signals are quite strong, tend to be shorter than contacts with nearby stations. When signals are very weak or station very rare, a contact may consist of nothing more than a confirmation that you each have a call signs correct and a signal report. To confirm contact, both you and the DX station must get each others call sign correct. To do that, use standard phonetics, speak clearly, and enunciate each word. New hams often don’t realize that multiple hops and skips around the world have a pretty dramatic effect on speech intelligibility, none of it for the better. Speak relatively slowly, don’t slur your words or mumble, and keep your transmissions short.
Ward Silver, N0AX