The editor that we use for designing of the PCBs is Eagle from www.cadsoft.de
It is a simple yet very powerfull PCB editor with backanotation between schematic and PCB.
Symbol definition
Supply pins have appended pin number after the name, for example VDD5 is a VDD pin #5
Pins are using orientation In, Out, I/O and Pwr-device is consuming power or Sup-device is power source
Pins that are active in 0 are prepended with /, for example /MCLR
Pins that have several seletable functions are named by one to three major functions, for example: IC1/INT1/RD0 with the primary function alligned to the edge of the package.
Package definition
generic packages are stored in SMT.lbr, to create manufacturer speciffic package, copy the package from SMT.lbr to manufacturer library and modify it there.
in package description write size of the package and pin pitch, e.g. 10x10mm pitch 0.5mm
Always verify that the package size and pitch matches the component package drawing in datasheet.
Verify that pin 1 of the package is marked on the PCB, the mark must be visible after component is soldered in place.
Device definition
In device description write brief description of the device and describe if there are naming conventions in the device naming, for example 103=10K