First of all, study the module datasheet carefully! Make sure all ground pins are connected to the same ground net. The supply voltage should be stable and noise free. For high power modules, make sure the power supply is sufficient. If it is battery operated you may need to add super-caps. Pay attention to the I/O connections, for voltage level compatibility, pull-ups and floating pins. The Reset pin must be available for external reset, or controlled by host MCU. Do also add the possibility for in-circuit re-programming connector (just in case a firmware update is needed). For the antenna output it is a good advice to add a shunt and series component, providing the possibility for antenna matching.
Last Update: August 8, 2017