I've recently been interested in learning how to sketch and draft. Luckily for me, DaveKern just went through an intro drawing class and had this advice when
I asked him how he liked the textbook for Drawing II:
No, not for this one. In my Drawing I class I read Drawing from
the Right Side of the Brain
by Betty Edwards. She makes some
psychologically valid points about how drawing works. To sum up, you
need to defeat the logical part of yourself that insists on assigning
and then manipulating symbols. As soon as you look at say, a chair, and
think "hey that's a chair", you're lost. You end up drawing from memory
about what you think a chair should look like, even though the thing is
right in front of you. Drawing well all comes down to observing well.
As my prof said then, if you can write your name then you already have
the manual dexterity.
Some specific tricks that help. Try drawing from a photograph or
illustration, but turn it upside down and draw what you see. This
confuses the left brain enough that it gives up and you start
concentration on the patterns of lines and contrast that you are seeing.
That of course is the trick: you are never drawing a subject as an
object, instead you are merely recording the patterns of light and dark
that you are perceiving with your eye.
Another trick for complicated shapes is to concentrate on the
surrounding "negative space" and draw that. For the chair example, it
is easier to draw the openings in the chair legs/back then those
Another thing that helps for larger drawings is to draw a grid on the
source photo/illustration and then a larger grid lightly on your drawing
paper. You can then use that as a bit of a ruler to better judge
lengths and angles. Holding a pencil out at arms length does help as
well - but you look like more of a dork.
Above all... practice. ;-)