What are the most common leaks for a losing/break even player?

[excession]

lack of discipline (most commonly tilt and playing too many hands - esp OOP)
overvaluing trap hands like KQ and AJ in raised pots..and misplaying overpairs, AK,AQo post-flop
fancy play with limping and min raising big pairs pre-flop
cold calling HU out of position without very good reasons
trying to bluff calling stations
weak leading draws into opponents who are awake
paying off calling station when their draws hit
not making villains pay enough for draws
failing to value bet on the end
not understanding pot building and pot control concepts