While this advice is the best one I could give in my opinion, if you've already learned a monologue that you love and is working for you, just stick to it, but here are some things that I would avoid when finding a monologue that you want to memorize:
- no monologues with long pauses, you don't want people to think you're done if you're not
- nothing dull or boring, if you make one person yawn, it might spread like a wild fire
- nothing too long, if you're well over a minute and a half, you better have a good reason for that
- nothing overly emotional. If you can cry on cue, great for you, but cry-pretending, laughing and yelling is not always seen as great acting
- use something that screams "you" - if you have a certain skill, or want to be associated with a specific characteristic, try to find something that will emphasize that?
Always prepare, and practice. If you want to read your monologues out loud and need someone to listen, have your friends come over and practice with them. If that's not an option, try We Rehearse and work with other actors online. If you've made some connections on Stage 32 that you feel comfortable asking for favors, get a Skype session going. Practice it until you're comfortable. Only then use a monologue you've gone over and over. If you're gonna try and cram something just before an audition, it might backfire.
I'm not saying it's impossible to learn a monologue fast. If you need to learn how to memorize a monologue, check out this Wiki and this Backstage blog but keep one thing in mind - if you've got something memorized and you're about to go for an important audition and are considering learning something brand new, please, think twice.
As a stand up comedian, improvisation is important, but it's the routines that I've said over and over again that just flow smoothly off my tongue and get the biggest laughs. Monologues work the same exact way, the only difference is that your audience will neither boo you nor applaud you, well unless they DO applaud you, in which case you've got something great going on.