Define the purpose of the computer
Choose compatible components
Get a case
Get a power supply
Get a motherboard
Get a CPU
Get CPU cooling
Get RAM
Get storage drive
Get a graphics card if needed
Get a monitor
Get a keyboard
Get a mouse
Get speakers or headphones if needed
Prepare a clean workspace
Ground yourself
Install the CPU on the motherboard
Install the CPU cooler
Install the RAM
Install the storage drive
Install the motherboard into the case
Install the power supply into the case
Connect power cables
Install the graphics card if needed
Connect front panel cables
Connect case fans
Connect storage and data cables
Check all connections
Close the case
Connect monitor, keyboard, and mouse
Turn on the computer
Enter BIOS or UEFI
Verify hardware is detected
Install the operating system
Install drivers
Update the system
Install needed software
Test the computer