PCB layout always plays a critical role in the entire PCB board manufacturing process. Unlike the schematic, PCB layout aims to arrange the actual components to the exact location on the PCB and show the trace to connect each component together between the PCB layers. As we all know, the higher number of layers you design, the more complicated and expensive the manufacturing is.
PCB boards are divided according to the functionality, such as power supply, audio output and more. Then make sure you have grouped components of each section in the same area, so you can keep conductive traces short and reduce noise and interference.
The user interface is also something you need to keep in mind when designing your PCB. Locations of the components like audio jacks, connectors, LEDs, etc. need to be adjusted for the best user experience possible.
You should pay enough attention when arrange component placement on the PCB board, which is really matters. Some components might interfere with each other and cause unexpected behaviors. For example, if you have both, Bluetooth and Wi-Fi modules, they have the same 2.4 GHz bandwidth and can interfere with each other if not placed correctly.
When you finish the layout design, you will produce a Gerber file which is used by your PCB manufacturer.