Painted front panel, as well as top exhaust filter white.
Lights are usually kept blue.
I noticed that it was getting a little warm under the PSU shroud. I bought this little Noctua NF-A6x25 PWM fan to give a little extra airflow to my hard drives. I've noticed others have cut a small hole to fit a 120mm fan without removing the whole cover, but I wanted to keep it a little more hidden, and have airflow only for the hard drives. So far it has helped, they don't get over 33°c when they used to get to around 45°c.
Custom sleeved all white cables.
This is such a long process if you haven't done custom sleeving for long. After a lot of research, wrong cables and many hours I was finally able to get all my cables done. I'm very happy with how they turned out, but I would suggest just buying them if you're planning on custom for just your PC.
I, like probably everyone else spend way too much time looking into upgrading parts when it's not even needed. So far I think I am finally at a point where I am 90% happy with the build as is. The only thing I would change is swapping out my current fans for the all black Chromax, with white vibration dampeners.