I learned that you cant have free standing pillars without supports to keep it standing. This is because things can't they wouldn't stay standing. I also learned that everything needs to be to scale. If nothing is in scale then things won't be to size once you create it. The last thing I learned is that you need to make sure that everything external stays hidden within the model so that it stays clean.
One thing I learned about electricity and wiring is it use electrical tape when you're wiring. I say this because I learned the hard way... I plugged the battery in but I didn't see the wireds tangled and it started to smoke. So I pretty much almost started a fire with a battery.