As Huddy says starting off with tidying cables might be a little bit like running before you can walk
However in general most cables will only fit where they are meant to (but some can go in the wrong way round and risk damaging the motherboard*)
If you do try to tidy up the cables make a note of where any that connect to the motherboard went, and the orientation (the motherboard manual will help in general, but even with the manual things like USB can be a PITA).
I basically started with zero knowledge, but a couple of handy books (well before the internet was available), and the habit of taking notes when dealing with something i've not done before has helped many times (both with computers and when taking anything else apart, including my mother's washing machine

).
These days if you run into any problems, or have anything you're uncertain of either a google, or asking on the forums will get an answer most of the time
*Things like the firewire, and USB connections to the case are quite often individual wires rather than keyed blocks that can only fit in the right socket, the right way round.