@Awesomenatious
There's always something to learn here

I started off in exactly the same boat and have learned a lot in a few months. Still always have questions but there's always someone in here or a post, thread etc. with the answer.
I wouldn't worry about mixing parts and not following an exact build. You can mix up the core components any which way you like really. Just search the forums and ask around.
As for the cart reader, personally I found this bit easy. I used the PRS tech cart as opposed to making one (Wermys first guide). Wiring the cart reader to the Pi was also pretty straight forward and I've had no issues using it. Just take your time and test
I recently completed my first build (see signature) and im pretty happy with it. I've since re-seated my Pi and exposed the HDMI again, too for completeness.
Looking back on my first build I was scared of messing up, mainly for fear of breaking things, having to start again, waiting on parts etc.... no im pretty confident with what I doing but like anything else....as soon as you change something it poses more questions / problems to solve, like the USB audio as above.
Im currently building my 2nd GBZ using a simple Button PCB, teensy etc. Everything Is done except for the sound. As of last night I made and tested my Low Pass filter so this week ill wire up the volume pot and headphone jack etc. Then im just waiting on custom cart labels and the screen cover from Dominator
Good luck with your build - feel free to ask and Q's and if I can help I will.
If you're using an AIO by the way then @helder has a thread in Lounge full of info!
