Elbow–fingertip = twice head length

What you'll get with these measurements is a more or less accurate rendition of a human - but it won't be the human you're trying to draw. That requires you to look closely at your subject - it may help to keep broad perspectives in mind, particularly that the top part of the head is a lot bigger and deeper than we tend to think it is, but the general advice in how-to-draw books seems to be written on the whole by people who have forgotten to apply their own practice to the advice they're giving. The same is true of the advice in so many books and articles on painting, which offer a standard procedure the artists themselves probably haven't ever followed and certainly don't now. That's why I wrote my own modest tome on oil painting: I couldn't see how the readers of some other works were supposed to understand the basic steps which some authors had just taken for granted, and certainly didn't explain. I have several books on drawing - from the very simple to the much more advanced: and yet I don't think any of them is really of the slightest practical use: the only method I've encountered that is would be the Bargue course championed by Daveyboyz, whose usefulness he has proved. There is also the danger of getting too prescriptive on the other hand: e.g. it's noticeable that many of the painters who follow the Ron Ranson approach do produce paintings looking rather like slightly less accomplished versions of Ron's. So a balance needs to be struck between giving applicable advice, and holding people's hands to the extent that you're almost doing the work for them. I don't think most artists are professional writers, publishers aren't artists, and an awful lot gets lost between the two of them.

I agree that those proportional diagrams have limited use. The problem is we're all expert on how people should look, and can spot when something is wrong. We may not always be able to define clearly what's wrong, we just know. In my own case, I like to draw cartoon style quite a lot, because it gives you freedom from all that, but gives problems when you go back to drawing normal people...especially when making it up...I frequently get the legs too short, for example. I guess having a model to work from is best...but that's not always possible. Lew.