Before I go any further, I do want to say that I am afraid there are no short cuts to excellence. You can be given endless numbers of short cuts and hints about how to draw but at the end of the day, it is only by copious amounts of practice of many of the basic principles of drawing, that you will achieve good quality in your drawing skills.
So - let's just take another look at the business of using PLUMB LINES plus a couple of other pointers - I have highlighted them in bold for you. I have touched on plumb lines before - the idea of working with a mental grid - but it was a while ago, so I am going to mention it again because I keep seeing students' work which does not take them into account, yet they are so very, very useful.
Here is a quick, student line drawing of a dancer:
On the face of it, not too bad...the weight of the dancer seems to be on her left, standing leg, which seems logical and right; her head is tilted forwards; there is a suggestion of three dimensional form. The arm on the barre looks a bit thin and there is an odd bulge on the other arm, but in general...not too terrible.
But let's look at the original source photo.
And let's use PLUMB LINES to re-see the two images, to find out where the other problems are. The natural inclination for most students is to draw the outline of the figure from the photo, and then "fill in" the shadows. But the problems seen in the drawing will become clear when I use plumb lines which have nothing to do with outline, and everything to do with seeing with more accuracy.
- Check proportions carefully
- use plumb lines in both directions to check positioning,
- observe curves, and changes of direction, by using a straight edge for comparison
- observe the play of light which gives us the form.
- observe negative shapes around the body and between forms - these often give us extra clues to us.
- spend a little time studying the anatomy of the human figure. This can only add strength to your drawings, both of the nude, and of clothed people (you often have to envision the form beneath the fabric of clothing), and will help enormously when the photo is inadequate and needs some reinterpretation.