When playing poker, either online or in a live poker room, one of the keys to profitable play is careful observation of your opponents. Online play is often aided by third party software providing heads up display or HUD but even when using HUD it doesn't mean you shouldn't pay careful attention to your opponent's betting habits and patterns. In a live poker room there is simply no substitute for careful and concentrated observation of betting patterns at the table. They are the most important tells at the table.
Many players transparently bet when they have a solid hand and check or fold when they do not. Some even vary their betting and bet stronger when they have a monster and weaker when their hand is merely strong. But they check or fold when they are holding poor hands. Against these players, those who are reluctant to voluntarily put money in the pot, I generally will go away if they bet into me but if they are checking I will most certainly make a bet of some sort.
There are players who love to chase straights or flushes. They bet into boards that are highly textured toward either a straight or flush or both. If I am in front of them and the board is textured I will generally bet between three-quarters of the pot or a pot sized bet to price this draw out. If I am called, so be it. If I don't have the flush cards I might muck if played back at, but I find these players generally reluctant to go beyond the turn if they are not holding the flush or straight. If I am in position and the chaser bets into me and I have a hand worth playing I smooth call and buy a free card on the turn or river.
Then there are those players who always lead out if they raised pre-flop. It is statistically unlikely that the flop hit them, leaving them with a mid to strong pair or a drawing hand. I almost always smooth call the C-bet unless the player tends to be loose or semi-loose and then I might raise with any two cards. The smooth call sets a trap for later streets if I am holding something solid. The raise may take the pot right now which isn't a bad thing either.
Then there are those who act with aggression both pre-flop and on the flop but suddenly turn timid on fourth street. Poker takes the courage to fire another bullet on the turn if you fired one on the flop. It takes even more courage to fire the third bullet on the river when you are bluffing or think you might be second-best. With these players, I know I am beat if they fire a bullet on the turn but if they check the turn I become hyper-aggressive and look to take the pot then and there.
Overbets on the turn and river generally, though not always, indicate a bluff. The rule of thumb is simply when you are acting weak you are strong and when you act strong you are generally weak.
Finally, there is the passive player who constantly underbet the pot. Often they simply min-bet because they are afraid to commit chips to the pot with anything other than the nuts. Even then, some timid players under value their monster hands. I once sat next to a guy at the Monte Carlo poker room who mucked a straight flush because someone bet into him. He inadvertently flashed his cards to be and I folded a set of kings. You can believe that whenever he had cards I raised his bets when I was in position and bet into him with a substantial bet when I acted in front of him.
One cannot define betting patterns from a single hand. It takes three or four times around the table, maybe more, to accurately define how one approaches betting. Even then, I am observant of changes that occur in what I identified as a pattern earlier.
While it is important to observe your opponents at the table, it is equally important to observe yourself and your own betting patterns. If I have been really fortunate and I have been dealt three strong hands in a row and raised with them, if I am dealt another I will generally either check or call rather than raise. I do not want my betting patterns to be transparent otherwise I will just be easy money.
I tend to size my bets equally no matter what position I am in or what two cards I have pre-flop. My standard raise is 3 times the big blind. It matters not to me whether I am under the gun or on the button or whether I have a 72 or AA in my hand. If I am first to enter the pot I raise 3 times the big blind. My standard C-bet is half to two-thirds the pot whether I have hit a hand or not. I am always willing to give up a hand if I am pushed and I haven't hit anything. That is about as consistent as I can be. When I mix it up a bit I will vary my opening raise up or down by a half a bet to a full bet and I will increase a C-bet to three-quarters of the pot. By acting with consistency, I am not giving away any hand strength or weakness. My hands remain unreadable. All that goes out the window, however, when I find that I am being played back at by weaker players. That means that I am getting little respect at the table and I need to change my strategy.