To view other tutorials on clerical script (隷書) please see here.
There are five main types of strokes in each of the Chinese calligraphy scripts. Those are vertical strokes, horizontal strokes, slanting strokes, curved strokes, and dots. Each of those has multiples variants, further multiplied by the calligraphy script types.
There are a few variants of slanting strokes on clerical scripts. They can be divided into two major groups, left slanting strokes and right slanting strokes. The pictured (above left) slanting stroke is a left slanting stroke, which means it slants to the left side. The key to understanding strokes in each script is to learn their characteristics and brush operating techniques. In clerical script, each stroke begins with a reverse brush movement (逆筆). However, not all strokes begin in the same manner. In fact, if you watch my other tutorials on clerical script you will notice those nuances.
However, the major difference between the strokes lay in the way of leading the brush (送筆, lit. sending the brush), and ending the brush stroke (終筆). In case of this left slanting stroke, the brush pressure against the paper increases gradually, when the brush is on its way towards the end of the stroke, which causes the stroke to thicken. Finally, at the end of the stroke, the brush stops, is twisted (the brush tip marks a circle). During marking a circle, the brush pressure is lessened until the brush leaves the paper surface. See below video to see how it is done in practice.
There are no more or less important strokes in Chinese calligraphy. All of them create the balance, build the character structure and even a single dot, which is badly placed or poorly executed, can ruin the whole work.
Ponte Ryuurui (品天龍涙)