I think that one of the strategies of poker is to determine how people play, usually a person will always have a model of plays or a pattern that they always follow, and that can be quickly determined by at least one machine in a casino, but for people who play actively at a game table requires a little more time, when it comes to playing physically it is easier because of their gestures, but when it is in a digital game way it is more difficult, I think the most easy to see is when bets are made and some check and some don't, I think that's a way that you can take into account to determine if you can get a person's style of play, but of course it's not entirely reliable .
I don`t think that playing in the internet easier than playing in offline casino. This is just different types of game. In online poker you don`t see the opponent, but the opponent doesn`t see you. That`s why you can concentrate on the game. And you don`t need to read the opponent, you spend all your time at cards. I think that it can be a problem to become offline player if you played only online before.
Since we can't see the opponent's expression, we can only guess what he will do and how he anticipates it. Maybe by looking at the number of bets he made or other things, it can be a clue for us to find out if he has good or bad cards. But still, it can't be a sign because he could be bullying his opponent without us knowing. Maybe instead of buying a poker lesson, it's better if we learn how to play poker ourselves so we don't have to spend money to buy it.