Wow, what a question: If you had to start all over again???
I joined this "hobby" in March of this year and did not know jack-all about high-end 2 channel audio. Still don't profess to know much but am investing the time, effort and unfortunately the hardest part, the money, to learn! If I were to start over, I would run away as fast as I could. No, probably wouldn't but I have a hard time explaining how frustrating it is to start-out in this hobby with no knowledge. You don't really know what you want and you don't know where to turn for solid advice. If you go to the Big Box Stores they don't know crap about 2 channel systems. If you go to one of the high-end stores you don't really feel comfortable (I didn't anyway) because the prices are spooky if you have had no exposure to quality gear.
So, getting back to the topic I believe it would be beneficial for the experienced Audiophiles to create an advice topic addressed specifically to green newbies (as I was) on how to best approach this hobby. I think starting out it is very easy to get it wrong and difficult to end-up truly happy with the first high-end system. I have had a lot of help from the members here and at AC and I still have some mods to make.
I think the answer to the question: If I could start over and know what I know now? Hell, I don't know the answer. There is so much gear out there!
Ken