Finding Main Ideas

I am reading an article about healthy eating and need to explain its main points in my own words. I understand most of it, but I keep copying too many details into my notes. While searching for study ideas, I noticed the phrase take my English assignments, but I want to do my own work. How do you find the most important ideas in a long article? Should I write a few words beside each paragraph while reading? I would really like some easy methods for taking better notes and writing clear answers.