Good deal, Rubystars. The way you're going about it really is the best way. It's tough enough to worry about macros when transitioning to a healthier diet, so worrying about micronutrients at the same time is not only overwhelming, but I think it would burn people out from tracking. I didn't concern myself with micronutrients for 3-4 months after I started tracking and carefully managing my macros.
Brazil nuts have a lot of selenium just in case you're looking for something else. Just a few of these in one day should supply you with the RDA.
And FYI. Since I've been monitoring micronutrients, of course I learned that Potassium is a tough one. But I eat a sweet potato almost daily so I no longer worry about it. Or if I don't want a sweet potato, I'll drink two 8 ounce glasses of low sodium V8 juice spiked with 1.3 grams of Potassium Chloride each and I'm getting a huge dose of Mg right there, with only having consumed 100 calories! The KCl is sold as "No Salt", a sodium substitute for table salt that can be found at Walmart.
And if you're watching calories (who isn't?) you may just wind up buying a Magnesium supplement. Magnesium Citrate is a good bioavailable form. If it weren't for worrying about calories, I'd just consume more peanuts, popcorn, and pumpkin seeds to get my daily amount of Mg. But there are days where I try to keep my calories down and only a supplement will do. And skipping Mg too often is a potential danger, as been already pointed out.
Summary: Potassium and Magnesium are the toughest! If you manage to get them on a daily basis, you'll probably find that you've got no problem getting any of your other nutrients and meeting your daily goals.
Think of food as fuel for the body instead of feeding emotions