How should you generally identify your station when attempting to contact a DX station during a contest or in a pileup?
Why In a pileup the DX station is working many stations quickly, so the goal is to give him everything he needs in the shortest possible transmission: your complete call sign, sent once or twice. Sending the full call lets the DX log you correctly on the first try instead of having to come back for a repeat, and it satisfies FCC identification requirements at the same time. Extra words like the DX station's call, grid square, or signal report just waste the pileup's time and slow everyone down.
Watch out Sending only the last two letters is a habit some operators picked up, but partial calls force the DX station to ask for a repeat and are not valid identification under Part 97. The long "his call three times, this is, my call three times" format is old ragchew or net practice and is far too slow for contest or DX work.
In a pileup: your full call, once or twice, nothing else. Short and complete beats long or partial.