Playing the Player
It's been said that poker is not a game of cards played with people, it's a game of people played with cards. There's definitely some truth to this, and even at "no foldem" tables there will be times when you read on particular players can contributed directly to your profit. At most brick and mortar cardrooms there is usually at least one person sitting at the table that is almost savant in their ability to interpret other player's betting patterns and tells and make great raises and laydowns, even on the river.
Of course, the more solidly your opponents play the easier it is to put them on a range of hands. If you raise pre-flop on a fairly tight table you can be relatively sure that no one called you with Jack Five offsuit whereas at a live low limit game you have no such guarantee.
In either type of game it is still worthwhile to improve your hand reading ability, and while that does include putting them on a range of hands and trying to make sense of their general betting patterns with legitimate hands it also very importantly includes their betting patterns and tendencies with draws and bluffs.
One critical thing to note is that each opponent will approach different situations in a different way, so there is no single way to determine if someone is bluffing a failed draw at the end, or raising on the flop with just a straight or flush draw. You need to observe a player through many such similar situations to see how they play and then further refine it to see how they play the same situations when they're on tilt. When you have that information you can make much better decisions.
Here's one good example for river play. At any particular game there are some players which are incapable of a bluff on the river, so for example against a random opponent if your hand has progressed this way:
You are betting on each street and your opponent calls each street. When you bet the river your opponent raises, what do you do? In most cases you would have to call here against an unknown opponent. However if you are up against a never-river-bluff opponent then clearly you should fold here as they definitely have you beat.
However even on a scarier board like:
You might fold your hand to a raise from an unknown opponent, but if you are up against someone who will try a river bluff-raise with a hand like Qx or 8x you need to be able to make the call here. Differentiating between these two players is crucial and even a tool like Poker Tracker won't give you easy information about what to do here (without custom database queries)--what will give you information is observation of your opponents, which is what you need to do to improve your poker game at all levels.
A similar situation happens on the turn. When raised (or check-raised) on the turn, knowing your opponents tendencies is critical. Again, there are some players that will only make this move when they can beat top pair (some are even more conservative than this!) while some players will attempt a raise here frequently on a semi-bluff hand. For many players if they bet the turn and get raised they will always call, however this is often the wrong action. Against people who frequently semi-bluff here a reraise is often in order, and of course against people who will only raise here with two pair or better you need to evaluate the strength of your current hand and its possibilities of improving on the river.
You bet and your opponent raises on the turn when the king of hearts comes. Without knowing anything about your opponent you should usually fold here, but if your opponent frequently semi-bluff raises on the turn this is a likely spot to reraise for value as there are a wide variety of hands your tricky opponent might semi-bluff raise here and there is also a very strong chance that a scare card will come on the river which you may want to check and call vs. a tricky or aggressive opponent to induce a bluff if they miss their draw.
Some opponents will be very aggressive on the flop with a flush draw. Obviously you are not going to let go of this hand on the flop even in the face of aggression, but if you feel you are up against a flush draw and you are up against a single opponent you may want to let them drive the betting if you are in position. If your opponent bets into you on the above flop and you raise and they reraise you should usually just call because regardless of what comes on the turn they will probably bet out again.
If a card comes on the turn that doesn't appear to complete any obvious draws you can raise the turn forcing them to put at least one extra double-sized bet when they are a severe underdog to your hand.