From a Dominants point of view, begging for something verbally would have to be "please". It's not ever the repetition that makes it satisfying but the tone. If something is asked in a "proper" tone then it appears to be more satisfying. Whimpers, moaning, purring, and gestures are all submissive and encourages. Kneeling is a good gesture so is the lowering or cast off of eyes. Another thing is a teasing look. One where the submissive looks up slightly then immediately looks down. It indicates the need to please the Dominate despite her/his own needs.
Light nuzzling, nibbling, asking simply for permissing to do something and having a submissive posture are all other ideas. Doing something that the Dominant really likes. For example, I have a hair fetish and a good way to beg me for something would be to kneel and to accent with her hair being down around her shoulders in a pleasing way. All of this contributes to the beg and submission to that Dominant in particular.