The rule of thirds is a rule used by artists and photographers in relation to composition. How does it work? Divide your paper into thirds as shown and place your subject in the area of the one of the circles indicated below:
I believe and I am sure most art teachers will tell you that drawing from life is always better than drawing and painting from photographs. I think particularly if you are learning to draw then drawing from life is essential.
Of course there is nothing wrong with drawing and painting from photographs and while working on illustration commissions I have in the past used many references from photographs an images. Sometimes it isn’t possible to observe the subject in life.