Moisturizer primer, powder THEN foundation. This is the best foundation application trick I have yet to discover. It gives me the smooth, flawless, glowing skin I've been wanting. It's not really what you use, but the order you use it in!
Take a piece of the inside of a banana peel and gently rub around on your teeth for about 2 minutes. The amazing minerals in the peel like potassium, magnesium and manganese absorb into your teeth and whiten them.