The real key to reading a person

What does someone mean when he says "reading a person"? I think a lot of you out there correlate that to some sort of physical tell. Although tells can be useful, they should almost never be the sole factor in making a decision and they are only part of "reading a person" . The more important pieces of the equation are the tendencies and patterns you can pick up from an opponent's play of previous hands. The expert player has paid attention to hands each of the players have been in to know what his opponent bets out with and what he calls with and what the most likely street he'll fold on. The expert player also attempts to make sure he isn't making reliably predictable moves so he is harder to read.

So what are some things to look for to get a better read on a person? Below are just a few ideas and questions to answer (there are millions more!) so you can change your game based on your opponent's tendencies and patterns. Note that none of these factors which I'll discuss should be used independently. They form a collective of information about each player which needs to be viewed as a whole to make decisions.

1) Does the player lean towards aggressive, passive or straight forward?
Aggressive players like to fight with you over pots. When shown weakness they will pounce and even in the face of strength sometimes they'll try to make a move on you. My best attempts are not to fight fire with fire. I usually sit back and wait for a good hand and let the aggressive opponent hang themselves.
When a passive person checks it doesn't necessarily mean weakness, but it doesnt mean you should always check to the river with them. Depending on other factors, I'll tend to take one shot on a bluff and value bet the whole way down. If they fight back with a bet or a big raise, you should believe they have a big hand since they normally sit back quietly calling off all their money.
A straight forward person will be when he has a good hand and check when he has nothing or is on a draw. If you have position on them, fire away on the flop when they check. And tend to check a few more flops out of position if you aren't sure where you are at because they may just tell you. If they check behind on the flop, fire away at the turn if it isn't too likely the turn hit them.

2) How many hands do they play preflop and what is the quality of those hands you get to see?
You have garden variety preflop tight players that only come in with solid quality hands like pairs and a couple big hards. Thus your range of hands you put them on should be fairly small and easier to act against.
If your opponent play loose preflop however, it is much difficult to put them on a hand but it is much more likely they have a shakey holding after the flop. Definitely never think to yourself, "no way he has this hand because I raises preflop!" I have actually seen some players call signficant raises with any two suited cards and some play damn near 100% of hands!

3) How often do they call on the flop and with what range of hands?
Some opponents will call with just about any piece of the flop hitting their hand and even sometimes with just overcards. Yet some will only call if they have top pair or better. This is a huge factor in deciding whether to fire the next round of betting. If you have top pair, go ahead and value bet the person who calls with bottom or middle pair.

4) How often do they call on the turn and with what range of hands?
Sometimes a player will call on the flop just to see if you have the stone to fire again on the turn. When you do fire, they scurry away. When they do call a turn bet however it should give you a pretty big indication as to possible hands they hold. Look at the board on the flop and then the turn card to decide if the turn may have helped them or if they are calling with the same hand they had with just the flop (ie did the turn complete a draw they may have had on the flop or was it a blank).

5) What type of hands are they betting with on the flop or turn or river?
The previous two points dealt with your opponent calling you. What if they are the ones doing the betting? Will they bet top pair all the way to the river or will they check the river thinking the pot is big enough or trying to snap off a bluff? Will they bet a draw on the flop but check on the turn? How often have you seen your opponent checkraise and with what range of hands?

This only scratches the surface on this very important topic in big bet poker of knowing and understanding your opponent. Think up some other ideas on your own to fit into how you read an opponent.