EAGLE is the well know CAD application for designing PCBs.

https://www.autodesk.com/products/eagle/free-download

Hackaday Tutorial

• Introduction
• Part 1
• Part 2
• Part 3

Packages

• Sparkfun library for many common parts (https://github.com/sparkfun/SparkFun-Eagle-Libraries) ¨
• IAD library  https://github.com/IAD-ZHDK/IAD-Eagle-Library

Design Rules

• Use Sparkfun Rules as default (https://github.com/sparkfun/SparkFun_Eagle_Settings)
• Draw 32mil wires
• Change Clearance also to 32mil

Ground Plate

• Draw a Polygon around the PCB
• Select Info and Set Isolate to an appropriate value
• Select "Ratsnest" from the Toolbar to calculate the ground plate