People who are new to poker tend to think that reads are about putting the opponent on a particular hand (say a king, which made a pair on the board, and a small kicker), but figuring out what hand the opponent has is very difficult. If you try to put somebody on a particular hand and act accordingly, chances are you will guess wrong and pay the price.
What you should do when an opponent makes a (non-fold) move preflop, is you put him on a range of hands based on the situation and what you know about this player from previous hands. Then you make the move that works best against that range. It would of course have been a lot better if you could pin-point the exact hand he has, but you can’t and so this is the best practical option.
The next move he makes in the hand will help you eliminate some of the holdings from his initial range. This continues for every move he makes. Only very rarely do you get to eliminate so many hands from his hand-range that you are pretty sure that he has a particular hand.
Of course, sometimes unexpected stuff happens in a hand and you have to revaluate the hand-ranges you put him on in previous streets, but this is a good approach to putting people on hands.
Reads are not limited to putting people on hands, it is also about figuring out what type of players you are dealing with. Just like the correct move on your part depends on what hand your opponent has, it also depends on how the opponent would play that hand. In other words, the range you’ll assign a tight player who raises preflop will be a lot smaller than the range you’ll assign a loose player who raises preflop.
I believe this is an opportunity where most profitable poker players could improve their game even further. They might be good at putting people on hand-ranges and figuring out their style of play, but actually using that information to optimize their game is an even further challenge.
The easiest adaptation you need to make is loosening/tightening your preflop hand-range depending on how loose and how aggressive the players at your table are. If you are facing a raise preflop, you will naturally need a stronger hand to stay in the hand if the raiser only raises with good hands. This becomes especially important if there are one or more short-stacked players at the table; you do not want to raise with a marginal hand and face a difficult decision whether or not to call a short-stack’s all-in.
If it folds to you preflop and there are mostly loose players behind you, you need a good hand to raise because you can’t expect to steal the blinds often enough to make raising with a mediocre hand profitable.
These are obvious situations that most profitable players know how to handle, but here is one situation they may not handle well:
It is folded to you, and the players behind you are largely loose and very passive. Many would say you would have to tighten your hand-range in this situation because you won’t be able to steal the blinds often. But what they are forgetting is that since the players would only re-raise with premium hands, they’ll probably just call if they decide to play the hand.
This is great for you in several ways.
1) Since they are loose, there are probably many hands in their hand-range which are so weak that you stand to make more money from them calling with those hands than folding.
2) Since they are so passive, they rarely force you to fold by making a re-raise when they have a strong hand. So you get 3 free cards (the flop) when you have the weakest hand.
3) The rare times they re-raise, you know they have a great hand, and can fold with a sigh of relief that you only lost your raise when you could have lost a lot more if you hadn’t known what you were up against. For this reason, I would much rather meet a loose player who would only re-raise with premium hands, than a loose player who would never re-raise.
When it is folded to you preflop, you should generally be tighter the looser the opponents behind you are, and tighter the more aggressive they are. But a lot of good players (and poor players too of course) ignore or don’t fully take into account the aggression-factor, while everybody and their grandma know to adapt to the loose-factor.