Sai-Jin,
It's always ok to use score as a motivator. After all, that's the ultimate object of the game, to shoot a lower score. Just don't let the score become so important that it ruins your enjoyment of the game.
I keep thinking of additional questions to ask you. Do you plot your misses? For example, this isn't my card but it's how my scorecard (before I started using Golflogix) used to look:
I also mark what side I miss the fairways or the greens on. This way I know that if I miss on the left I'm far more likely to card a bogey or higher. If I miss on the right I've still got a shot at making par or at worst, a bogey. Basically then I know that no matter what I do, I can't miss left. I think there are even software packages that will help you with the %'s.
It'll help you key in on where your misses tend to be! :)