Any tips for first-timer replacing PSU and Graphics card?

[Aryube]

hiya, thanks to the forums replies for helping my choose these; Graphics Card and PSU (I know the gfx card is voltage locked).

I've been looking at Youtube videos but I wan't to ask if anyone has any tips for a first-timer replacing his PSU and Graphics Card? This is my current PC if it helps.

Also if there are any easy mistakes I should know about, thanks!

 

[Aryube]

thanks for the replies, i went and bought myself an anti-static wristband too