The most important is to use a ground plane where all ground pins are connected with as shortest possible traces. For this reason the board must be two layers minimum. The ground plane will also be a part of the antenna, if using a PCB or built in antenna. Place any noisy devices (such as DC/DC switching regulators and displays) away from the RF module. The antenna connection should be closest possible to the module RF pin.
Last Update: August 8, 2017