The best way is to keep it simple. Use the barest description, declare it a gift and value it as zero.
I frankly don't think customs cares as long as something is written on the form. The green forms are for smaller, lighter packages. You must use the larger white forms for bigger packages - those measuring over a certain number of inches - and/or heavier ones. I think it is anything over eight pounds.
My son and I have been sending boxes of all sorts of things for more than four years and I quickly learned to fill out the minimum on the white forms, rather than list twenty different items.
When sending any kind of food, I mark it as "snacks", notebooks, pens, pencils, etc. are "school supplies", personal care items become "soap" or "shampoo", bedding (towels, sheets and pillow) might become "Pillow". Boxes of stuffed toys, toys, books and magazines need only a plain word or two description, but if I also include any kind of food or snacks, which I often do to fill up any empty spaces, I write "(name of item) and snacks".
I have had boxes make it from the east coast where I live to Bagdad in five days. The only delays I have had have been with oddly shaped boxes, like the time we sent donated baseball equipment in a long patio umbrella box that we stuffed so full it was diamond shaped. I am sure customs was curious about that one, but it made it to Kirkuk eventually.