Hello
Can anyone suggest me how to create milk shader?
You can use subsurface (radius 1,1,1) of principled shader and mix with glossy shader. Here is the file if you want to take a look: milk.blend (1.5 MB)
That milk is far too rough. Also, Principled already has glossiness, so no need to mix it with a Glossy shader.
Also, in the colored Subsurface Radius section, color it so that R > G > B and make the Subsurface Color off-white.
Any realism further than that is due to advanced modelling challenges like adding bubbles.
So, in essence, take Principled, give it SSS, give it an organic distribution of SSS radii (I like 1, 0.75, 0.5, make the color slightly warmer (0.8, 0.75, 0.7?), and lower the roughness to ~.1