Zhongruan's left fingering skills include independent flat fingers, relaxed shoulders, natural curvature of elbows, wrists, and finger joints, and strong support of fingers and palms.

Use the knuckles to drive the fingers up and down, not the power of the wrist, the fingers and the strings need to fall vertically, and the strings cannot be played when pressing the strings. The position of pressing the sound is on the upper side of the fret, and the joints of the fingers need to master the strength. , the fingers stand firm and strong, flexible and relaxed, and the landing point is accurate.

When the left-hand glissando is played, the body of the thumb rest moves with the portamento position, and the pressing finger consciously slides up and down on the strings to obtain the sound.

Ruan's glissando can be divided into push-pull string glissando and fret glissando. Pull glissando refers to the horizontal sliding of fingers on a string, all done on one fret, while fret glissando refers to finger pressing and sliding up and down a string. Can also be done on multiple frets.

There are three kinds of gradation slides, namely, the small slide up and down, the big slide up and down, and the fast slide up and down. For intervals other than the third, slide up and down the fret for the second interval.

It should be noted that the speed of the left and right portamento should be uniform, there should be no pause during the portamento process, and the fingers should glide at a constant speed until the portamento is completed.