Pay attention to your opponents.
Few intangibles would influence your results in poker to the extent that your level of focus would. 
You could learn what to expect from each of your rivals simply by paying attention to the action. This would not refer strictly to the times you would be involved in a hand: rather, you would have to be watching every hand, whether you were to be involved or not.
By concentrating on the game, you would learn which poker players play loose, tight, passive, and aggressive, and how their position would control which hands they enter pots with. Once you would have a good read on their play, you would be able to start developing effective tactics for beating them.
Although holding on to a basic strategy would help you become a winning holdem poker player, which alone would not be enough. You would also have to make changes based on the other poker players in the pot. Poker has been a situational game, and each situation would require individual analysis. Here are two examples in which knowledge of your rivals would allow you to make the appropriate choice.
Early Raise
You couldn’t treat an early-position raise from a poker player who would be raising every fourth hand the same as you would be treating an early position raise from a poker player who would seem to be raising only every fourth year.
This would have to be quite evident. The first poker player could easily have a hand like an ace and seven or a king and jack offsuit if he were raising regularly. Hence, you need not be overly anxious of this action. Instead, you should be re-raising with any hand that you would typically be raising within your position. Ideally, the hand would then be played out between the maniac and you, and would have to be holding the best hand most of the time.
But if it had been the tight player who was to raise in early position, you would have to fold all but your very best hands. You must say to yourself, ‘this guy hasn’t been raising since the Carter administration. Just what could he have?’
The answer, of course, would only be a few hands: a pair of aces, a pair of kings, a pair of queens or perhaps an ace and king. So, it wouldn’t do much good to call his raise with a pair of jacks. It would be a nice hand in absolute terms, but this would be the time to toss it into the much (the discard pile). Also, if you were to be holding a pair of queens, you would still be in trouble.
Your rival would either be a big favorite with his overpair, or close to even money shot with an ace and king. In holdem poker, if ever there would be a time to pass a pair of queens, this would be it. If you would stick to playing only a pair of aces, a pair of kings, and an ace and king suited when a super tight player were to raise, you wouldn’t be contributing to his account.
Limp
You should be treating a limp tight poker player differently from that of a loose one. When a tight player were to call, he would be far more likely to be holding a quality hand than when a loose poker player was to limp. The tight poker player would not enter the pot with trash. Just because he hadn’t raised the pot, you couldn’t assume he wouldn’t be holding a quality hand.
Tight passive players would generally just call with hands such as a pair of tens, an ace and queen, a king and queen suited, or possibly even an ace and king and a pair of jacks. Keeping that in mind, it would take a monster to raise the pot behind him. If you were to hold a hand such as an ace and queen or a pair of tens, you would usually be better off just calling a limp by a tight poker player.
Alternatively, you could play aggressively behind a loose player’s limp, in an effort to detach him in the pot. It would nearly always be a advantageous situation if you could play a pot heads up against a weaker hand. If a loose poker player were to limp and you were to be on or next to the button, you could raise with any of the hands you would have played had it been folded around to you. This could include poker hands as weak as a king and ten, which would still figure to have a decent chance at being the best hand in this situation. Plus, you would be holding the benefit of position.
There are good odds when calling half a bet in small blind.
Suppose three poker players were to call the first bet. You would be in the small blind with half a bet in. 
What price would you receive from the pot on this call? You would have to put in half a bet, and the pot would contain nine half-bets (inclusive of the big blind and your small blind ) already. So the pot would be laying you a price of nine-to-one.
This means you would have to win only one time in ten for calling to be correct, assuming no additional betting. However, there would be additional betting, and your positional disadvantage would also have to be considered here. Hence, you would have to be holding a halfway decent poker hand to complete the bet.
A broad rang of hands would be worth a call, though. Any two suited cards would do, as well as any hand that was to consist of an ace. Furthermore, any two connecting cards nine and eight or higher would be worth a call. Poker hands with one gap (cards not adjacent in rank, but separated by one rank) smaller than a queen and ten must by and large be folded (ten and eight, for instance). Any pair would be playable from the small blind. Some of these hands would need to be hit pretty solidly by the flop for you to continue, but they would possess the potential to develop into big poker hands.
The former guidelines would be applicable to games with a one-two chip blind structure (such as the one dollar and two dollar blinds in a two-four dollar game or three and six dollars in a six-twelve dollar game), in which the small blind would be exactly half the amount of the big blind. Still, you might find yourself in a poker game with either a one-three or two-three structure. This would have a huge impact on how the small blind would have to be played.
For one-three chip poker games, you should treat the small blind as you would a late position hand. If the hand wasn’t worth a full bet from late position, is wouldn’t be worth two-thirds of a bet from the small blind. Of the types of poker hands listed formerly as playable, suited trash and bad aces would now have to be folded, as would connectors such as nine and eight and ten and nine offsuit. Small pairs would still be worth a call, as would medium to large suited connectors.
In two-three chip games, playing the small blind would be exceedingly simple. If two or more poker players were to have called, you would have to call with everything! Yes, even a seven and two offsuit* would be worth an extra chip in this spot. You just shouldn’t get carried away if you were to flop a deuce. The time to consider folding the small blind for one-third of a bet would be when only one poker player was to have called, you would be holding a bad hand, and the big blind were to be a recurrent raiser. As long as those conditions weren’t all there, though, you must put in the extra chip.
* This hand would be singled out because if would be the worst possible holding in any game with more than just a few poker players. In a short-handed game, a three-two offsuit would be the worst.