Where do you study? How? What? Books or youtube or practice? Please give examples
This is something you're not gonna learn from any book. This is something that comes over time put in at the tables. It involves observation, regardless of whether it's live or on-line, and that means when you're out of pots, especially then when you have no stake in the outcome. The fish are plenty lazy when it comes to this, and live venues have ample opportunities to be distracted.
On-line players have their HUDs and stats, so they also get pretty lazy. You only see when you observe, and how the vills are playing today may have nothing to do with how they played just a few days ago.
It helps to not try to read the whole table at once. Pick one player to watch. How often is he in pots? Does he open for a raise, or is he a limper? Does he do both, and how frequently? Does he c-bet, and into what kinds of boards? Does he donk if he has flatted a raise? With what? Can he double barrel? Triple barrel? Is he a "one and done" if his c-bets are called? Is he FoF? Bet sizing
tells: does he have any? Is the amount he raises correlated to hand strength, either positively or negatively, or position dependent? How does he bet a routinely good hand v. the nuts? Can he bet for thin value with hands like TPGK? When he gets to showdown, what does he show: lone pairs, or two-pair or better? Does he show
bluff hands? If
bluffing, doe she do this with missed draws -- straights and flushes -- or with whiffed Big Slicks and Little Slicks, and on what board texture?
Any tells, and that includes live and on-line. If on-line, determine if he's multi-tabling or not. If not, then is he a button smasher, or does he think about bet sizing? How fast does he hit the buttons? Instacalls tend to indicate he already made up his mind before the bet was made, and that usually means a good, but not great, hand. If he hesitates, what does that mean? Doubt about calling with something marginal, or was he contemplating whether or not to raise and by how much? When raising, is he still just smashing buttons, or are there odd bets sizes in there? Does he seem to be unaware of stack sizes, and does he sometimes leave a short stack with something behind when he should have gone for the full stack?
When on-line, keep the chat turned on and pay attention. Mostly, it's meaningless, but sometimes you can tell who's steaming based on what they type. You can tell which regs know each other, and determine if players have it in for each other. See if they mention strategy -- it's almost always the fish that do this, as they like to throw around buzzwords, but don't really understand the concepts, and it shows in their play.
It's all about paying attention at all times and avoiding distractions.