I am interested in a career in cencept art, and was looking for a few tips. I have been drawing for quite sometime and draw every single day. I am in school to get a degree in animation and illustration. My question relates to those little straight lines I always see in mechanical concept art. I am guessing that those are guidelines of a sort, but what is the method used to set them up. Does it have something to do with perspective, vanishing points, ect. Any help would be appreciated. Thanks!