For me...the best part of the tickle is the begging beforehand. I like to do little, almost insiignificant things that induces the intended "victim" into becoming a desperate, giggly, rambling, begging little girl.
My super-ticklish ex-girlfriend, for example....
She was REALLY ticklish in her tummy and sides....very soft, pliant skin in those areas....and whenever she needed to be taught a lesson for her sass-mouth, I would chase her down and straddle her legs while holding her tightly by the wrists. During the chase, she's already pleading....but when I would trap her and then begin pulling her shirt up with my teeth....slowly exposing her middle, she'd be giggling and yelling and writhing something awful, knowing full well what was about to happen to her. I'd talk to her....describing in intimate detail what I would be doing to her.....then punctuate these statements by probing and rubbing the tip of my nose against her tummy, just underneath the bellybutton. By that time she'd be out of her mind, which is when she'd be ready for the final strike...a half an hour of having her creamy middle nibbled and licked all over.
Man, as they used to say in the NBA ads: "I love this game!"