the problem i used to have was losing patience when a run of bad cards hit me. Ive got better recently at playing tighter when such a run occurs.
Obviously your bankroll will take a hit during this time which is why its always best to stay within your limits.
Ive said this before elsewhere, if i start playing badly or feel myself going on tilt (weve all been there) i either drop limits or if im already playing at a lower limit, start playing freerolls and play money games til my game picks up