A bit of advice for new players

The bad beat at the bottom of last post reminds me. I've often been playing and seen players justify drawing at slim odds by saying "I only needed one card to make my hand." I want to examine this thinking, because not only is it the wrong way to approach drawing to hands, but saying something like this at the table immediately lets the experienced players at the table know they're up against a novice.
For those of you who read the post where I talked about not putting your money in as a huge dog, I'm not attempting to insult anyone's intelligence here - I see this kind of thing at the table all the time.
Okay, so let's back up a little bit. When a player says they only need one more card to make their hand, it means they have either four cards of a suit and are drawing to a flush, or they have four parts of a straight, usually a gutshot. However, in both of these situations, especially with only one or two cards coming, the person who "only needs one more" is usually a huge underdog to win the hand. Not only that, by calling and drawing to these longshot hands, they are giving their money away in the long run. Here's an example -
Say you're playing no-limit hold'em, and the pot is heads-up. It's the turn, and you have four cards to a flush. Let's also assume that there's $100 in the pot, and $100 left in your stack (we're using round numbers to simplify the example). You feel that you have to actually hit the flush in order to win the hand. If your opponent bets $100, you should absolutely always fold.
Good poker players understand that when you have a straight or flush draw, you "only need one more." The relevant question though, is how likely you are to get it. With four parts of a flush on the turn, we've seen six cards (four on board and two in the hole). Thus, there are 46 unknown cards left, and nine of them make our flush. Therefore, we'll win this pot only nine out of forty-six times, on average, or about one out of five times (20%). This makes calling a losing proposition, as we can see below:

If we call the $100, four out of five times we'll lose that $100, but one of five times we'll win $200 (the pot plus our opponent's $100 bet). Mathematically, we can calculate the long term expected value, on average, for calling with the four flush:

[ (4/5) x (-$100) ] + [ (1/5) x (+$200) ] = ?

( - $80 ) + ( + $40 ) = -$40

so, we could expect to lose $40 on average each time we call in this spot.

essentially, calling to draw to the flush there is equivalent to giving away $40.

This whole argument is the reason people say "don't draw to inside straights." Although that maxim is not always correct, the instinct to stay away from longshots is correct. The pot has to be offering you extremely good odds. In the flush example, your opponent's bet would have to be considerably less in order for you to correctly draw to your flush, or you would have to be able to make up the difference in pot odds with future betting if you make your hand.

The biggest reason I'm highlighting all of this, is that the number one mistake from inexperienced players is unnecessary looseness in hand selection and postflop play, and it makes them marks. There is no way to be a good poker player if you don't get your money in there when it's good, and avoid putting it in there when you don't have the best of it. Maximize your mathematical expectation. That's the whole game.