My husband has ADHD. Two out of our three children have ADHD, and the third is four, so time will tell. I don't, as far as we can tell, although sometimes I wonder about myself! My husband is an enormously informed patient when it comes to his disorder, and we've put a ton of reading, thinking, conferring and support-group leading and attending into how best to parent kids with ADHD.
Here's what we know about it: It's highly genetic, and is a function of dopamine re-uptake in the brain... which means it has very, very little to do with fruit, refined sugars, screen time, toxins in our water supply or anything else other than the way your brain processes dopamine. That's the science. You can do what you want with that information, but the research is what it is.
ADHD kids and adults need a lot of coaching for executive function. Our school really helps with that, because they give all the homework at the beginning of the week, and it's all due on Friday, so we walk the boys through creating a homework plan every week, and how to think about their other commitments ('So, you have a project due on Friday, but you have Karate on Thursday. That means your project has to be done when? Right, Wednesday!').
They have a great role model in their dad. We talk really actively about ADHD, including my husband being really candid about the things that are hard for him, so they'll see Dad and I discuss how to break down and handle complex tasks and how he can calm down and handle things one at a time when he's overwhelmed. We use a lot of checklists and to-do lists in our general family life, and are teaching the boys how to use paper and technology as an adjunct when they need to remember or organize something.
We make sure the kids are getting good sleep and good foods (whole foods, complex carbs, good fats) with no caffeine, which can mess with their meds. We talk a lot about balance -- my kids are inattentive and are easily sucked in by screens, but need to learn to manage their own screen-time needs, and their play time versus work time. We play games that encourage strategic thinking and executive function as a family. We teach meditation and breathing to calm impulsivity and help make good choices. The kids do music and martial arts and science. Their dad and I work at ADHD-focused, forward thinking parenting constantly, 24/7/365.
Still, the number one thing that has helped my kids has been the Focalin that they take daily. I say this without a single doubt. Meds have literally made the difference between being socially excluded and damn near expelled from school to now functioning like normal, bright, geeky little boys. Your mileage may vary, but for us it's like refusing insulin to a diabetic.