I am a physics PhD turned application programmer who got into systems programming the hard way.

My design skills are such that i can make something good probably half the time on my own.

You're right that a small investment in learning will get you some big gains.

One thing that helps is sticking to some standards. I worked at web dev shop that had a standard for forms that we called "Spider Forms" that might not have been genius but it is better than what you'd get without a plan and cheaper (and still better) than what you would get bikeshedding it with a client.

I like anime art because it designed to be easily reproducible by many people. I got good at drawing these guys

http://hyperdimensionneptunia.wikia.com/wiki/Dogoo

It's the only character I can draw but I can draw them quickly on blackboards, whiteboards, etc. My son lately has learned how to draw characters from Starfox and Sonic.

I used to think about color theory but these days I just find a picture that has a color scheme I like and copy the color swatches.

I think many people would be better off if they stuck to a small set of fonts and did not think about typography. If people put a lot of effort into it they often end up doing worse than if they took the defaults. For me the really interesting aspects of typography are the "less travelled" paths such as "what do you do if the text is too big to fit in the space?" and then shoehorning it in by changing the letter spacing and squeezing the letters.

Then there is the rule of thirds. Learning that didn't make me into Ansel Adams but it vastly improved my photography overnight.