Match the size and shape of the PCB with the box you are going to use. Finding a suitable box for a ready-made PCB is usually harder.
If possible, take into consideration the standard parameters and technological capabilities of PCB manufacturer to optimize production costs.
If possible, make the printed circuit board rectangular and place the components at a minimum of 5mm from the edge. This way you can make efficient panel.
Determine the place of the fixed components - connectors, heavy and high components, cooling radiators, through hole components that go beyond the board, etc.
Place all components on one side when possible.
If the smd components have to be on both sides, place the heavy on one side, along with the through hole components.
Position similar components in one direction.
The signal traces between the components must be as short as possible. Place them in one layer horizontally and the other vertically.
On more complex PCBs, place power and ground traces in separate inner layers.
When the printed circuit board has a high and low voltage, it is advisable to separate the power circuit from the low voltage circuit.
Take into consideration the temperature parameters of the components.