It doesn't really matter. I have been doing bodybuilding for the past 2 years+ now and I've taken them both at the same time. Arginine is an amino acid, it basically promotes more blood flow in the veins and oxygenating them. Ginkgo promotes better mental function although I don't take it anymore. As for dosages, I'd say 3-5 grams of L-arginine daily and ginkgo, I'd say 250 mg or less. And take em on an empty stomach too. Food can diminish their function.