Reading your opponents for the most part comes down to identifying what poker style they play with. Knowing what poker styles you are playing against will help you become a winning poker player because you can make adjustments in your play.
LAGs (loose aggressive) play many hands, very aggressively. Extreme LAGS are maniacs. They rely on luck and tend to have very big swings they will occasionally have big wins, but more often have big losses. Their undisciplined play will tend to confuse you, which adds to their success when theyвre running hot.
LAPs (loose passive) play many hands, very weakly (few raises, many calls) I call these players lambs (calling stations). This is by far the worst player. They see almost every pot and almost every street and almost never maximize a win (unless someone else is doing the betting for them). They could have the nuts and may very well check/call (which can be a bit confusing, but at least itвs not as costly as losing to a LAG!)
TAGs (tight aggressive) play few hands, but play them very aggressively (ideal style) players who can play this style well, tend to do very well they typically maximize their wins and control their losses.
TAPs (tight passive) play few hands, but play them very weakly (lots of calling and folding) also known as rocks, they tend to be winners, but fail to maximize their wins, but do minimize their losses. They will get very little action because they are so rarely involved in a hand that any one with half a clue will get out of their way. Watch out for the check raise from these guys.
So what poker style should you integrate into your game? This is a hard question to answer. I think it comes down to your natural style and whatever you are comfortable playing. Whatever style you are playing, you never want to become too predictable because the good players will pickup on it and you will get owned.
I like to play against LAGs when I am sitting to their left. If you are playing solid poker and have patience, you will always get them in a spot where you have a premium hand and they have overplayed a pair, and you will get all their chips.