JimmyHo - what about taking advantage of position? also falling in love with an over pair. Article seems more geared to cash games.
Monteroy I am assuming this is being written in a brief general manner for basics of the game. I would combine points 2 and 5 along with some other extras in a category I would simply call BET SIZING - People bet way too small at times, not realizing their bets have no chance to cause anyone to fold - People bet way too big at times when only hands that can beat them can call (your all in on a bluff is a bit of a specific off shoot of this) You can add all sorts of examples to this category. Your errors 1 and 3 are fine, so is 4 for tournaments I would also say a failure to appreciate the power of position is a huge error in a lot of players as well, though not sure that discussion is for the article you wrote.
GTA Poker IMO not even close to the top 5. Bankroll management, discipline, emotional play, game selection, stop-losses, not playing with tired, etc all supercede these in becoming a winning player
Graham Thanks guys for the feedback. I didn't actually write the article, but will look into doing a better one for another site. Appreciate the feedback.