Ok then.
Wear anti-static wrist strap attached to grounded case.
Handle hard drive with care, 1 drop can damage it.
Of course remove an GPU and addon cards before removing the motherboard.
Depending on orignal case you may have to remove memory or other items to be able to remove hard drive if its a tight fit.
Other then that it is really straight forward, remove what is in your way first.
Assuming case has no restrictions/fitment issues: I typically install power supply, motherboard, hard drive, dvd drive, add on cards, any other hardware, sata cables, power cables, front headers in that order.