Dont go making a whole heap of hasty tweaks at once if you arent well acquainted with what you are changing. Make a couple of changes at a time and even take notes if necessary as to how/what you changed.  Once you are satisfied the change isnt a problem to you.. move onto the next item.  In doing this if something goes pear shaped you will be able to easily and quickly back trace your steps and change something back to a more suitable setting for your PC.

Whilst taking notes is a little tedious.. I've found in the past on occasions it has been a blessing to and saved me a lot of time and frustration.  Its also been a good way to learn about my computer and OS