i just found myself using this random trick that one of my art professors taught me and i thought other people might like it!
-at rest, the elbow hits the bottom of the ribcage, and the wrist hits the bottom of the crotch
-the distance from your inner elbow to your wrist is about the same length as your foot
-the length of your hand (from wrist to the tip of your middle finger) is about the same length as the distance between the bottom of your chin and your hairline
so, if you have a feeling that proportions are wrong on something, those work as quick gauges. like, if a character’s forearm looks too long, try to visualize their foot being the same size and see if that works. if the hands look too big, look at their size in relation to the face.
hope this helps someone!