Look at this drawing. We will start with general proportions. As you may note, I measured the figure's size in head lengths. Plus, most artists start with the head. This makes a body look somewhat impressive and heroic, but that's not what we are looking for.
Young humans have larger heads than adults.
You can see the most important proportions of the skeleton in the drawing. I will now give you some aids that help the actual drawing. Also note gender-specific differences that are especially important when drawing women. Do not approximate the lengths. Watch perspective correction, but I will deal with this later.