A few considerations:
Backed up any files you want to keep?
Access to Internet?
Start reading here:
Have a solid state drive? (I hope you have a really small star screw driver.)
Find which parts you have and read up on them.
I've found it is helpful to create a folder with all my system information as some manufacturers remove documentation.
Your going to need some method of getting the OS on the computer.
USB/SD Drive or Optical are common options, with a Net Book unless you have an external optical drive the USB/SD Drive are probably the best options.
I opted for the USB Drive option. This destroys the contents of the drive and you might have to take some steps to start using it for regular storage again. Since I was writing the system from Windows I used the USBWriter program.