I tend to metagame when pirating. I know, what a scumbag.
I use the trader's level as a rough guide to judge how much cash the trader has. If he has a big fancy transport but he's only lvl 60 or so, he's blown all his money on the ship and won't have much to offer, so I don't ask for much. Better off to wait for 'em to do a run or two, then they can offer you more.
If they're high level, they're well-off and can spare some cash. I don't usually ask for more than 1 million, unless they misbehave or have misbehaved in the past.
I generally try to be polite when I ask for stuff from traders (unless I've had a 'hard' day) and I don't open fire unless they are proving to be non-compliant, usually after multiple warnings.
