This is about the easiest of all useful campsite improvements, But, beyond its simplicity, it’s just plain functional, adding mucho convenience!
Take three sticks, about 4 feet long and sharpen one end of each. (Tomato stakes work great.)
Hammer them into the ground deep enough to stand firm, spaced about 18 inches apart and forming an equilateral triangle.
Now place the edges of a plastic trash bag over the ends of the sticks.
Finally, secure the bag in place with a piece of cord using three Open-End Clove Hitches. Two 3-foot cords or a 6-foot lashing rope does just fine.
Self-Standing Garbage Bag Holder
SCOUT PIONEERING 
I found this very helpful. Thank you!