I think I used to set goals for sessions, but it's a really dangerous path to walk down since it may fool you into playing for a shorter or longer time than you should. If you can't catch decent cards, you won't be up that night, and no staying up until 4 a.m. is going to change that. If you sit down at a table with 8 maniacs, you might double your buy-in within 10 minutes. That's no reason to leave the table, on the contrary!
Try not to gauge results over as short a period as one session. But if you notice that you're consistently ending up in the red, try to look at some reasons for why that might happen. The most common reason is playing too loosely pre-flop, followed by playing poor and marginal
hands to the river. The amount of money you lose on playing a big hand and losing might seem like a lot, but it's peanuts comparatively.
In a big pot you may lose 5 big bets. A fish at a table loses that much by playing too losely preflop in less than three full rounds of the blinds, by just calling to see the flop. Why do people call a raise preflop with 95s but won't raise the turn when they have an overpair to the board and no reason to expect being behind? Costs as much, but in the latter case they actually have a reason to do it.
Whoops. I think i went off on a tangent.