Everyone has a story, as the saying goes. You might be from any of a dozen different backgrounds, but a few things tie you together with others that you will work with from time to time.
You are all SINless - it doesn't matter why, or how, that is for you to decide. If you're from the streets, then you never had one; if you're from the corps or some other sector of the "civilized world" then you have arranged for your former identity to be deleted from the databanks. Many may establish new identities through various channels, but these are forgeries, and will eventually leak out through the databases in the light of day.
You are one of the few that stand between order and chaos, right and wrong, honor and disgrace. You must decide. But always remember that you do not exist - you are a "deniable asset" that can be used to further someone else's goals. The trick is that you find a way to fulfill your contract and use it to your benefit to achieve your own goals. Whether it is a quest for a life of luxury, revenge against a certain corporation for perceived wrongs, or just to maintain the status quo between the powers that control the world around you, it is up to you, and you alone, to control your destiny and achieve your goals.
Flexibility should be your mantra. From day to day, you will be challenged by various people, places, and "things". You need to learn to adapt and change in order to survive. The ability to negotiate and successfully give-and-take, whether it be during a business deal, or looking at the wrong end of a combat shotgun, is an important skill. Plan ahead, and be ready to have contingencies in place should something unexpected happen. Know that you will have to work with various people, and you will not always be able to depend on them to watch your back or have the same ideals as yourself - remember that for the short term, the goal in sight is more important.
Finally, remember that the age-old adages still apply - Trust No-one, Prepare for Peace by Preparing for War, Know Your Enemy, plus dozens of others. And of course, Never Deal With a Dragon...
So, here you will find some short works that will help shed some light, so to speak, on what it will be like to run the shadows in Shadowrun Missions. Take heed, and learn from those that have gone before!
The Razor's Edge - Some insights from a retired shadowrunner on your place in the world, your reputation, and how to make it to retirement... "
The Fox and The Hounds - No shadowrunner can survive long without a fixer - but just what does a fixer do, and what is their ultimate goal? Like 'runners, not all fixers are the same, but it helps to know what you could be dealing with...
Cast Off Your SINs - This article explains some of the "ins and outs" of credsticks and why shadowrunners are SINless.