hi mate, 3g twice a day;
Take first does first thing in morning on empty stomach.
On workout days take sencond dose 45 mins to 1 hour before workout, again must be on an empty stomach and taken apart from other competing amino's and whole protein sources. Also not a good idea to stack it with caffeine, I havn't got much time to go into that now but I made some pretty big posts in the last few weeks in the supplement section explaining why, so run a quick search on my user id and it'll turn up the relevent data.
Non-workout days take your second dose mid afternoon, again must be taken on an empty stomach for best effect.
I've been using arginine and NO supps for the past year with no apparent ill effects, I've heard of the one or two 'horror stories' mentioned on various other boards but I have yet to see anything concrete pinning these effects on the arginine and I'm sure if such horror stories were true it would surely have led to a fairly wide spread message to stay clear, which I haven't seen anywhere.