found this site with some good basic info, thought it might be useful to others.
http://www.expresspcb.com/ExpressPCBHtm/Tips.htm
enjoy.
Well,
I’m not experienced PCB designer - but even they saying “These tips are not specific to using our CAD software, but instead..” it seems to me, that those instructions are very much made for doing layouts:
A. Without prior netlist (ExpressSCH was introduced in -02)
B. For doing Double-sided boards..
Let’s say, that Double-sided boards are “forgiving” for stupid component placements you end up with if you can’t see “rastnet” while doing it 
Just place via here and there 
It’s a different thing altogether doing a single-sided board and having a continuous fight agains “jumper wires” or whatever.. As I can always SEE, what signals or nets are not yet routed I can and DO optimize component placement - and yes, it doesn’t stop even with fully routed board
Bye, Moebius
ok, this is true. But do you agree with the guidelines for track widths? I had not come across any anywhere else yet, and thought that was a useful item in the article.
If they say so
There’s a nice calculator: http://www.desmith.com/NMdS/Electronics/TraceWidth.html
and here’s the other one, giving slightly different results http://www.geocities.com/CapeCanaveral/Lab/9643/TraceWidth.htm
As you can see, there’s no “big mystery” behind it. Smaller traces will carry same currents as larger ones, but as having bigger resistances, will also warm up more. There you can also calculate trace clearances for different voltages..
There are some interesting articles at the source: http://www.ultracad.com
…But to the original topic: Download pdf from here:
http://alternatezone.com/electronics/pcbdesign.htm
It’s an excellent “paper”
There’s also lot’s of useful information scattered around http://www.epanorama.net
Bye. Moebius
good links, especially that pdf… Thanks!