First off, be sure to read all of the help files.  They aren't long,
and they contain information that is very useful, if not essential, to
the game.
    When you start the game your skills are all at 0.  Thus, if you die,
you're no worse off.  Therefore, spend some time getting acquainted with
the complex, and build a 'nest egg' of credits (by recycling scattered
items around the maze) before you start to raise your skills.
    When you finally decide that you want to play in earnest, buy a few
levels of consitution (for additional health points) and markmanship (so
you can actually hit your targets!).  Depending on how many credits you have,
you might also consider a few levels of dexterity, which will make you
harder to hit.  If you can find one, a shotgun or better is a nice weapon
to start with.  If you can't, you must buy a pistol at a store.  Don't forget
some ammo!  If you've joined a team, ask your teammates for a decent weapon
to begin with.
    The best attack strategy when you're just beginning is a hit and run.
Attack an opponent a few times quickly and run back to a medical facility
if you've been injured.  If things get too hot, leave the game and re-enter:
computer players will no longer be attacking you (although if you were
fighting a human opponent you would no doubt be dead).
    Finally, be cautious in all actions.  Brash moves usually end in an
untimely demise.