The Taoist sexology texts contain a variety of instructions for using deep and shallow thrusts in alternating patterns, but I think one version is plenty to give you the general idea—and all the benefits. You can find this exercise, called Nine and Nine in Chapter 13 of Sex Again: Recharging Your Libido where it will be explained in more detail.
To begin, the man will insert only the head of his penis into the woman’s vagina—nine times. Then the entire penis once. That completes one set of ten strokes. Next decrease the number of shallow strokes by one, and increase the number of deep strokes by one, and continue doing so for a total of nine sets. The full pattern looks like this:
nine shallow and one deep
eight shallow and two deep
seven shallow and three deep
six shallow and four deep
five shallow and five deep
four shallow and six deep
three shallow and seven deep
two shallow and eight deep
one shallow and nine deep
The pacing is up to the two of you, but in general slower is better. A lot of couples prefer slower entries and quicker departures.
Beginning with more shallow and moving on to deeper thrusts maximizes pleasure, especially for the woman. This alternates a feeling of being tantalized with a feeling of being satisfied, which is a highly pleasing combination for most women—and a good path to orgasm, even for women who haven’t been able to orgasm during intercourse previously. Doing the Nine and Nine can speed up the path to orgasm for women, and/or heighten the orgasm experienced.
While the varying of strokes creates a sense of anticipation that intensifies the experience for most women, for men it tends to spread out the intensity, helping extend intercourse by delaying his orgasm. That’s because the stimulation varies between targeting the head of the penis and the shaft. Stimulation of the entire penis increases desire to ejaclate; stimulation of the head of the penis alone decreases desire to ejaculate.
That said, one time through this whole exercise totals ninety strokes, and no matter how you spread out the area of stimulation, this can be a lot for many men. If you finish a set of nine without having an orgasm, feel free to do the whole thing over again. But if it’s tricky getting all the way through, just do shorter sets, at least to begin with. Do sets of five, or four, say. Whatever works for you.