looking at references of real people is probably my only advice.. life drawing is good if it’s accessible to you, but there’s also some great online references - I really like adorkastock :> looking at other artists can be a little risky because some (ME INCLUDED VERY MUCH SO) have dodgy anatomy sometimes, especially be careful when drawing women imo. Honestly though, most of the time i just use myself as a reference, especially for unusual hand positions, or poses with extreme perspective