Just because I've been running Shadowrun side by side with D&D lately, I've been thinking of a lot of Shadowrun style attitudes and tricks that certainly apply to Old School D&D. This is one of them, and something that my players have steadfastly refused to do in D&D (though its almost the first step most Runners undertake if they start to feel that telltale twinge about a run), and that is: Investigate your employer. In the shadows, in D&D, and in life people are not always up front about their motives. While there is an endless list of reasons for this the most important one stands out in Shadowrun most of all: they're trying to screw you. Adventurers, like runners, are expendable resources. They aren't the personal forces of their employers, but rather come-and-go mercenaries that might not even be trustworthy. Mercenaries, far more often than people who have strong ties of loyalty or fidelity, are often thrown to the dogs for some larger gain. That's one of their primary uses.
A number of reasons to investigate your employer:
They plan on using and discarding you. This happens so often in Shadowrun that its a whole trope. The devious fixer or double-crossing Mr. Johnson is a fixture in the field. While this is much less likely to be the case in D&D, don't forget... you're still an expendable resource.
They have ulterior motives they aren't mentioning. This happens more often in D&D and perhaps less often in Shadowrun, mostly for the reason that Mr. Johnsons never tell you what their motives are in the first place. Having ulterior motives in Shadowrun is the norm. Now, employers in D&D might have a thousand reasons for hiding their real motives, but learning them never hurts. At worst you can just help accomplish the task in the way they were secretly hoping. At best, you save your own life.
They might have powerful friends... or enemies. This is big because when you decide if you want to double-cross someone you gotta weigh all the risks. You don't want to return and tell your employer that you gave up on his job because it got too tough if he's in good with, say, the king.
They might have a bad reputation. This is similar to the one above. It takes but a minute to discover that your employer is well known for sending mercenaries into terrible odds, or failing to pay them at opportune moments. You need to know this stuff.
It will help you map your local political landscape. And this can save your life. Knowing the relationships between noble houses, where to turn when things look down, and how to get out of a kingdom if the law comes hunting for you are all important bits of information.