Arginine you want to take on an empty stomach. An hour after you ate or an hour before you eat at the very least.
Other aminos such as stuff you find in Animal Nitro, Leukic and any other Leucine based amino acid formula (including the liquid proteins that are cropping up everywhere) seem to tolerate food a lot better. I still take these right before I eat if I can help the timing.
Taking Leukic or Leukidrol or similar amino acid blends before workouts will help with fatigue and keep you anabolic during your workout. Don't neglect to take your protein shake after the workout.
Alternatively, you could skip the amino acid blend and go with a shake before workout and a shake right after. Make sure you're using a high quality, high bioavailable protein shake. Translation: dont go cheap.
As for the Amino acid blends for stimulating HGH. THey're a mixed bag. Only Scretagogue did me any good and like the other poster said, it has to be taken on a completely empty stomach which means at night 3 hours after you ate your last meal. The only problem with these blends is they seem to increase heart rate and blood pressure (don't know why), may interfere with sleep if you're a light sleeper, and I have heard that they speed the growth of cancerous cells. I don't know about the last part.
I have used them. If you have the money to shell out 120 dollars a month on night time aminos, they might be worth it but morethan likely they're not right for you.
Also anyone with any virus load, as in HIV, Hep C, and any other virus based disease should NOT take arginine. Please warn your friends about this. Arginine increases virus load dramatically. Avoid it at all cost if you're infected.