To begin Wavlink N300 setup, first, connect the router to a power source and your modem via an Ethernet cable. Access the Wavlink web interface by typing "192.168.10.1" in a browser. Enter the default username and password ("admin" for both). Follow the setup wizard to configure internet connection settings, including username and password provided by your ISP. Customize WiFi settings and security options. Save changes and restart the router for them to take effect.