Drawing from observation skills

We've done a lot of drawing from observation in the past few weeks, and we've needed a variety of skills to complete each artwork. Some overall skills that each of us needed were listening to directions carefully and paying attention in class, working hard and thoroughly on each piece, being able to stand up while drawing for the hour to 2 hours while working, being patient and not judging your art until its complete, and overall staying focused. Other skills we need (art related), are being able to draw with the right spacing/sizing fo objects, adding texture and shading (depending on light) to our picture, and really making the setting look realistic. The hardest thing in the process of our drawings, was getting to the "screaming point," where we would notice something that was completely off about the picture. However, we would use our skills we earned in previous classes and this class, to fix our picture and rearrange objects to correct our mistake.