All the components that need to set its location, such as connectors, switches, LED , mounting holes, heat sinks or other items mounted to an external location.
Give careful thought when placing components to minimize the long trail. Put the next section are connected to each other. Doing a good job here will make tracks much more easily placed.
Arrange IC only one or two orientations: up or down, and, right or left. Align each IC so that pin someone in the same place for each orientation, usually at the top or left.
Position polarized parts (diodes, and electrolytic caps) with the positive leads who all have the same orientation. Also use a square pad to mark the positive leads of these components.
Placing Power and Ground.
After the components are placed, the next step is to put power and ground. This is important when working with ICs to have solid power and ground lines, using wide traces that connect to common rails for each supply