I've learned to shrug, roll my eyes, and laugh at the 17 fingered hand.

Control Net on Stable Diffusion has a "hand and body" pose. You can individually place fingers if you use some other extensions, or you can find a real-life picture of someone whose hands and body are posed the way you want them and use that as a template. That might be over-kill, though.

Negatives help, you can also specify hands be concealed behind objects or whatnot. There really is no reliable method except training larger models, (eg SDXL gets it right a lot more often than standard SD models) or manually editing the image afterwards.

First I try to add +25 or +50 steps in the generation. Sometimes the limbs, hands, face are self corrected.

When the size/résolution of the hands or of the face are too small, I can't get what I want. The results are shitty whatever I try.

Also, the models aren't equal. Sometimes, I inpaint the things I want to correct and launch it with another model. It still does work well if I try on very small faces.