Disclaimer: I am sure there are many better ways to do this, and in the end every artist has to find thier own approach, but here's one I recently came up with and which I find particularly useful.

This is it, basically. Since I don't really have time for a proper tutorial right now, allow me to just quickly explain my current process of drawing hands using this small thing I doodled down in gimp (I know it's a bit wonky, but it gets the point across... I hope).

I normally start with sketching out the hand and fingers. As you can see in the middle image, there are some simple lines where the fingers are supposed to go - these serve only as a rough guide and to capture the basics of the hand movement.

Next thing are these ellipsoid shapes which indicate the volume of the fingers - and are super practical for perspectivic stuff. They also work well with a modular hand build, like those I use in most of my Bionicle-inspired drawings.

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Hands are evil, so observe them often, research, use your own hands for reference, and practise, practise practise! Then it will get better. Eventually. :3