I’ll go against the grain here and say sometimes the most overanalyzed advice about monologue selection is counterproductive. Everyone says pick something unique, something no one’s heard, but honestly? An audition panel has heard Hamlet’s soliloquies a million times, sure, but they’ve also heard a thousand mediocre renditions of obscure, off-off-Broadway monologues. The familiar text can be a gift—it strips away the novelty factor and forces you to focus purely on your craft, your interpretation. You can’t hide behind the unfamiliarity of the words. I saw a director friend say their biggest pet peeve is actors picking something 'edgy' just to stand out, but performing it without any genuine connection to the material. It becomes a party trick, not a performance.
Where I think the real impact happens is in the physical life of the piece. A monologue isn't a radio play. What are you doing? Not big, stagey gestures, but the tiny, specific physical actions that root the character in a reality. Are they trying to fix a broken zipper while confessing a betrayal? Are they meticulously folding a napkin while delivering a threat? That specificity does more to convey subtext than any inflection you can put on a line. It shows you understand the character exists in a world, not just in a vacuum of Important Speech. It also gives you something to do with your nervous energy, which is a huge practical benefit.
Finally, and this is gonna sound obvious, know exactly who you're talking to. Is it a memory? A god? The empty chair in front of you? But more than that, decide what you want from them in that moment. Are you pleading for forgiveness, demanding acknowledgment, trying to convince yourself of a lie? That objective fuels every syllable. I’ve seen too many actors deliver a technically perfect, emotionally available monologue that goes nowhere because there’s no drive behind it, no need. It’s just pretty words floating in the room. The impact comes from the stakes, from the character’s desperate need to use these words to change something, even if that something is just their own mind. Start with that want, and let the technique serve it, not the other way around.