It is my opinion that programs like Auto Cad and some of the other top of
the line products are so complete that in order to use them you really have
to take a training course or get a study guide and use it frequently to stay
breast of it all. They are very complex.
I especially like DeltaCad because it is much more limited in it's ability
and hence has fewer commands to learn. It is Intuitive so to speak, i.e.;
intuition almost tells you what to do. A trial version is available at
deltacad.com, and it only costs $39.95 if you decide to purchase it.
I have used it for a number of projects and I really like it. Even if I
don't use it for a period of time it is easy to get back into without having
to re-learn it.
If you begin everything at X=0 and Y=0 and make all lines positive numbers
that simplifies life considerably.