It is said that Ms Maathai, Assistant Environment Minister of Kenya, was impressed by the Japanese word ‘mottainai’. The idea of ‘mottainai’ is fairly well expressed by a Japanese college student as: It expresses not only regret for the material loss, but also regret for the process of making, getting or achieving something. This is the "mottainai" spirit.
I have gathered several translations from newspapers, etc.
1. Waste Not, Want Not.
2. What a Waste!
3. Don’t Waste Resources.
4. Wasteful!
5. Too Precious to Waste
6. Don't waste what is valuable.
7. Don’t waste it because it’s precious and limited.
8. Shameful to waste
In my opinion, these all work and mean nearly the same thing. As a slogan, which one, do you think, is the best? ‘Mottainai’ is basically an adjective, but as a slogan, it need not be an adjective in English. Also, do you have any other suggestions?
Thank you.

Anonymous wrote:

1. Think before buying, think before throwing. 2. Buy not, throw not.

If you say: "Think before buying, or think before throwing" it's because it's necessary to buy or throw somethings away so you don't may say "buy not and throw not"

I think you can buy and throw any stuffs you want, but they must be used correctly and thrown in a place where they're will be recycled and where they won't damage the nature.