Once you start from the plug in the firewall it is pretty much self explanatory. The connections only reach so far, if you get to where you cant make a connection something is routed incorrectly. I just did the same thing a few weeks ago, just take your time, go slow take some breaks as needed and don't get aggravated.
gnttype.org has a photo guide that has a basic layout of where everything is located.
Best of luck