Here are my most favorite ways of seeing people lose with their Weapons Of Mass Destruction:

1. Slowplaying Aces pre-flop.
   Don’t make a habit of slowplaying Aces. As Dan Harrington said: just call only a marginal percentage of the time, and when you do — try to do it with aggressive players behind you. You don’t want 5 people limping in to a pot. You want one, maximum two players in the hand. This is VITAL for the strength of your aces after the flop!
   
   
2. Not keeping your head straight.
   Yes, your aces are strong — but you can’t stop paying attention. Keep studying the board and the players around you — trying to stay on top of the game. Think about what kind of hands beat you, and if they’re likely to have called your raise pre-flop. Keep in mind that against aces, looser opponents are more dangerous than people playing only premium starting hands. With a J94 flop, the solid player made AJ tops (or a set). The loose player may have flopped J9 — and your aces might be in serious trouble.
3. Checking after the flop.
   With aces; BET. Make a continuation bet if nobody has bet the flop, and raise if someone else has bet into what seems to be a safe flop. Define your hand. Checking is giving free cards, and it’s stupid. Not raising is stupid to, unless against a very aggressive opponent, who might keep bluffing at a pot when he thinks you’re weak. Keep in mind though — he’s getting free cards too, so you’re taking a risk.
4. Putting someone else on a set.
   Yes, someone may have flopped a monster — but it’s unlikely. Decide on the flop whether or not you put someone on a set — it’s the right time. If he bets out, you raise, and he comes over the top. Make your decision based on his image and your instinct. Same when you get check-raised. Don’t second-guess, it’s the wrong play. Once you feel he hasn’t flopped a set, stick to it.
   
   
5. When it’s obvious your aces are beat — lay them down!
   4-card flushes and straights on the board are typical situation you don’t want to see. Let your hand go if you are facing a big bet in these situations. Yes — the other guy might be bluffing, but he’s probably not.

Aces are great — don’t spoil the fun yourself!

Avoid Distractions
Don’t drink while playing. We all know alcohol makes you do silly things. Some casinos will offer winning players drinks. This is not to be nice. The naughty casino people know if you drink you start to make mistakes. If you are playing online don’t sit and watch TV or the children whilst playing. You should be concentrating on what you are doing. If you are tired stop playing. You will only start making mistakes. Get some sleep, some exercise or some food or all three.

Use the Basic Strategy
Always use the basic strategy. Always. It is maths and you can’t argue with it. (Well you can but the maths will win) Even those times that you are dealt a bad hand, for example you have a 16 and want to stand when the dealer is showing a ten. By not using the strategy you increase the houses edge and we don’t want that!

In the end playing Blackjack is like anything else. Be disciplined and it will pay off.