I've discovered some food allergies (soy, bananas, oranges) which have greatly eased symptoms after removal (especially digestion problems).
Magnesium and calcium have strong influences on cardiac events (skipped beats, bounding pulse, etc), but I haven't been able to leverage them to eliminate symptoms completely.
Ginkgo is great for circulation and body warmth (probably specific to my own body chemistry though, as it sounds like most people don't have any reaction to it). Ashwaganda is ridiculous (for me).
I wouldn't be surprised if nothing I've learned applied to anyone else. I don't encourage anyone to follow my specific diet (except for avoiding refined foods), but I do encourage people to track themselves. It's quite empowering.
I shy away from prepared food, both because it complicates analysis and because I've noticed it has a higher chance of causing negative effects. It's unavoidable sometimes though. If I have a brand or a restaurant I'll note that, but otherwise I mark the item with ???? to indicate it's uncontrolled.
I spent a few weeks measuring everything so that I could build up an intuition. I can eyeball most things reasonably well. It's not perfect, but it's a good ball park figure which is all I really need for my analysis.
The depth of the food tracking isn't too great, just food item, brand, quantity. I'm debating starting to track cooking method.