This doesn't answer your question about learning how to draw on paper.
I guess that's been covered--get thee to a library or bookstore.

On the subject of CAD software, I realize it is expensive but may I
suggest a different way to look at it? Think of it as another workshop
tool. One that will help save you money and time in mistakes not made.
I doubt that anyone would argue against proper planning.

I find that by the time I've completed a drawing whether with paper and
pencil or on the computer, it feels almost like I've built the project
once and I go out to the shop with much more confidence.

http://www.woodshopphotos.com/albums...m/shopcab3.jpg
The link is to a drawing of a cabinet I built for my shop. although you
can't see it in the drawing, all parts were drawn as individual pieces
and "assembled" to make the cabinet. Duplicate parts were drawn once
and copied. Everything was worked out in the drawing down to the
joinery.

No, the software wasn't as cheap as a pencil and a pad of paper but it
is makes it easier for me to make 3D views which I am able to do on
paper. It also lets me "walk" around the model to ensure I haven't
missed something.

My .02

Dave