It can be tricky. Without supplementation I hit most of my RDAs if not exceed them substantially. I'm pretty close on potassium. I was over yesterday but other days not so much.
The truly difficult, very challenging thing, is keeping sodium low. The recommended daily maximum I bet is exceeded by at least 95% of the population (seriously). Keeping it under the necessary limit requires almost total avoidance of processed foods and nothing canned unless it specifically says low in sodium or none added.
Salads are great for us but I was unable to find a single dressing yesterday at Walmart (I looked for around 2 min) that wasn't chock full of sodium.