Mistake #2 is the failure to establish the position of the complete figure on the page resulting in a drawing in which heads, arms or feet end up getting unintentionally cut off because the artist has run out of room on the paper. The solution is to put in underlying structure lines first, over which sub-forms can be placed. Be sure to include the top of the head and the bottom of the feet in your initial rendering plus some extra space for the margins. It sounds simple enough but it is amazing how many people will forget to do it.
Mistake #3 is the unintentional straightening of angles on the model (angles are important because they show how much the model is leaning). It is done unconsciously on our part and must be compensated for continually. Because most people aren’t aware of this tendency the problem never gets addressed in their drawings with the result that the model looks stiff. The solution is to start to draw the angles just as you see them but then to exaggerate the angle further to compensate for your innate tendency to straighten things. The effect is that your drawing will appear to be more accurate. You have to go out of your comfort zone and force things a bit, but to the viewer the drawing will look more believable.
Mistake #4 is the equalizing of the proportions on the human body when in fact irregular proportions are the norm. Nothing is equal or symmetrical in nature even though it may appear that way upon first glance. The solution is to observe more closely and you will see the many uneven proportions that you didn’t see the first time around. To just being aware of the tendency is already a step in the right direction and will help the quality of your drawing. Another method is to measure the length of various anatomical proportions on the model and compare them what you have drawn – you will inevitably find areas where you have “equalized” measurements. The irregularities are what make the drawing interesting and demonstrate the artist’s ability to observe closely. Nature and life are full of surprises and so your drawing should contain a few as well.
Mistake #5 is not to consider the environment surrounding the figure, resulting in a figure that inadvertently appears to be cut out or “floating” in space. The solution is to include a bit of the environment in the drawing. It can be the smallest line, but it helps the figure look more solid and more grounded. For example, add a small horizontal line next to the heel to suggest the floor, or a smudge done outside of the figure to suggest the space – it is as simple as that and works like a charm! The old masters did this a lot and you may want to refer to them for ways to integrate the environment with the figure.