The new guidelines for Americans recommend no more than ten percent of calories from added sugar. And 70% of people in the US eat more than that. The WHO even recommends below five percent added sugars - not many people manage that today.
What is the source of all that added sugar? It's really quite simple: the largest sources are sugar-sweetened beverages, snacks and sweets - as you can see in this nice graphic. If you avoid all that you'll probably stay under the five percent level.
JAMA: New Dietary Guidelines Place Added Sugars in the Crosshairs