[ QUOTE ]
If you think you are playing well you should continue, whether you are down 3 buy-ins or up three. Remember it is all one long session!
[/ QUOTE ]
That's fine and good, and of course it's theoretically unimpeachable. However, in practice a new player in the cardroom for the first time WON'T know whether she's playing better than the competition, unless she has a good bit of online or home game experience. (The OP mentions his online experience but not how much he has.) Sure, it's possible to watch the hands other people show down and gasp at their profligacy in playing 10 [img]/images/graemlins/spade.gif[/img] 4 [img]/images/graemlins/spade.gif[/img] under the gun, but it takes a while to really get to the point where you KNOW you can beat a game even when you're down 50 big bets.
I would say, if the OP either
<ul type="square">[*]doesn't feel comfortable taking a huge loss due to variance at these stakes, or[*]doesn't KNOW that he can beat the game he's playing in,[/list]then he'd be well-advised to set a stop loss of 30 BB. If you hit it, no worries, just go home and practice at smaller stakes online before returning to the cardroom. Sure, -30 BB runs can be pure dumb luck -- but it takes experience to KNOW that your downswing is dumb luck.
Those of us who've weathered a few swings -- and I'm a newbie relative to many on this forum -- tend to forget how hard it is to distinguish downswings because of one's play from downswings because of dumb luck.