A really good piece of advice? Don't be afraid of killing off characters if they do something stupid. Or, if you need to show the rest of the group that you are dealing with some serious stuff. Like, I don't see a group of Jaguar Warriors and a couple of blood mages going down without at least ONE of the characters biting it. Especially when the Aztlaners have the drop on the group.
But, if the hacker's player decides that his starting character is good enough to try to hack Horizon's Consensus servers in full VR, and no assistance... Well, concentrate on the rest of the group while he makes up a new character. *shrugs* Everyone at the tables I play with always has back-up characters rolled up in case their main bites it. If you are starting a new campaign, and actually want that level of grittiness, just suggest that everyone have a spare character so they don't waste the rest of the session writing up a new one. Of course, around here we're all used to playing Paranoia, CoC, and a host of other games that feature character death or insanity. So, it all seeps into our Shadowrun gaming as well.