You would think that after everything humanity has been through that we would have learned to live together in peace. You would, however, be wrong. The chances of someone attacking you are likely, so when you do get into a fight, be careful. If you start a fight on Tau Station, the locals or the security cameras will be sure to call down station security on you, earning you a swift trip to the Brig to think about your choices. You might get away with a firefight or knuckle sandwich on other stations, however. Some stations are tougher on crime than others, and many stations simply don't have the same security resources in place to watch everyone.
If you want to survive, experience counts. A pre-Catastrophe veteran who's been studying aikido all her life and working security will still probably take out that young whipper-snapper who's inexperienced but spending all of his free time in the gym. That being said, all other things being equal, the time you spend working out could very well make the difference. Additionally, your armor, weapons, and the items on your combat belt are all important tools that can be used to turn the tide.
No matter how badly you're hurt, if the station has a Sick Bay, you'll be revived and held there until they're sure you're better. If the station you're on doesn't have a Sick Bay, and someone takes you out, you'll be spawned into your most recent clone. If you haven't gestated a clone in a while, this could set you back quite a bit.
Be careful out there! In our post-Catastrophe “society,” you can never be sure how safe you are, nor how easy a mark your intended victim might be.