[sdiy] PCB layout tips

[Scott Juskiw]

In AN-15 (Electronotes), BH suggests putting +ve and -ve supply lines 
in two parallel rows underneath the chips. This sounds like a good 
idea to me. Yet when I look at PCBs of various modules (from people 
on this list no less), I never see this in practice. Is there some 
reason why this is in fact a really bad thing to do?

Is there a PCB layout "do's and don'ts" list available? Would anyone 
care to share any layout tips for a newbie?