L-arginine improves blood flow. It also preseves the elasticity of blood vessels through antioxidant actions. Also it reduces cholesterol and other health benefits.
My comment was for you to research them and find the ones that you feel would most benefit your situation, not go out and buy everything that I am taking.
Nitric Oxide works, I used take it before working out a year ago. I used one made by Xyience, costs alot and i was worried of over working my body since i was taking alot of supplements for working out at the time so i stopped.
L-Arginine. Take it along with L-Ornithine (the second one is stronger, so a supp with it in there will be more expensive). I'd aim for about 3 mg per day of L-Arginine, or you could halve that and throw in .5 mg of L-Ornithine and you'd be good.
Try taking 4 mg and go to the gym. You'll get a pretty gnarly pump, at least I did.
So, I guess, stick with about 3 mg and you should see a difference.