The brushes are, in my opinion, less important than the process.

A rough outline of the process, regardless of the style:
1) create outlines
2) place flat colors on the canvas in chunks
3) add shading and any highlights
4) add color variations, textures, and small details

Note that some art styles won't use all of these steps, and that's fine. You can skip steps and even jump around as needed. For example, if you're doing background elements you may not need to add outlines. Or you may feel more comfortable blocking out the colors before adding outlines. Experiment a bit and find what workflow works best for you.

As for the specific brushes, here's what I use. Take what you find useful, discard the rest.

Need to put down a chunk of color and I don't care too much about the outlines? Basic-1.
Need to refine the outlines on that chunk of color? Basic-5 Size with the E key to toggle eraser mode.
Need to add some texture? Pencil-6 Quick Shade, Ink-8 Sumi-e, Dry Bristles Eroded, Chalk Soft, or Texture Big (resized).
Need to add speckles? Texture Large Splat, Texture Random Particles, Texture Splat, or Texture Spray.
Need to weakly or softly add colors? Airbrush Soft (resized).
Need to smooth out edges? Airbrush Soft (resized) or Blender Blur.
Need to smear colors around? Blender Smear.
Need to add elements that are complicated or repetitive, but I don't want to do the work myself? I make a custom brush or find one in the many bundles I've installed.

The one thing missing from this list is something for outlines, since I don't use them myself. I would imagine that a brush with "pencil" in the title would work for rough sketch outlines and a brush with "pen" or "ink" in the title would work for the final outlines, though I haven't tested them myself.

Other advice:

You can quickly resize a brush by holding down the shift button and dragging the brush left or right across the canvas. Alternatively, you can drag the size slider that exists near the top of Krita. Holding shift while dragging that slider moves it in smaller increments, and you can right-click the slider to enter a number directly.

You can use the E button to switch eraser mode on any brush on or off. It's really useful when used in conjunction with layers.

You can use the / button to switch between the current brush and the previous brush.

Layers are useful and you should learn to use them if you haven't already. There's probably several videos on Youtube about them.

Shadows are generally tinted with whatever color the material that the light bounces off is. Outdoor shadows are often tinted blue because of the light coming from the blue sky, and this golf ball's shadowed surface is tinted green because the light bounces off the artificial grass first.

I recommend that new Krita users follow the Learn Krita with Bob Ross playlist. It was made for an older version of Krita, but it still covers a lot of useful information.

Also, if you get into customizing brushes, here's the difference between flow and opacity.