I think as long as you are coming out ahead you are doing well. After all, poker is a negative sums game for the players. I can only base my number on personal experience and from what I have heard, but I think a good number to strive for would be about 1/5 of the buy-in per hour, per table. I believe this goal is reasonable, but would get harder as you move up. If you are only playing one table and you are taking detailed notes then you could probably do better. If you are playing multiple tables then your +EV for each table decreases. In six man tables you could probably make more per table but its more difficult to multi-table.