A lot of critical decisions when playing either poker tournaments or hold'em cash games, requires you to put your opponent on a scope of hands. If you're able to do this with reasonable precision, your decisions at the poker table will invariably become rewarding over a period of time. However, determining your opponent's hole cards is certainly one of the more difficult aspects of the game to get really good at. Here is how you can start improving on it now.
If there is a single guideline to follow for improving hand reading, is to watch every player's move, even when you are not involved in a particular exchange. This is important online or in live play because it isn't just expressions or bodily tells you are watching but betting patterns too. When your challenger plays out of his normal pattern, then you must stop and ask yourself why. Usually this means his hand is atypical too, indicating quite good, or very poor.
Noticing your opponent's positional play will allow you to assemble solid assumptions about the strength of his hand. If he plays a lot of hands, his positional play won't mean much, but if he is by and large tight, solid hands from early position are rather customary, while opening up the range in later position.
Look at your opponent, not your cards when the deal comes. Glaring at the board is often the result of his hand improving. Looking away, or a quick check often means a potential draw or total miss. However, if he raised preflop and aces or face cards land on the flop, be careful of a trap.
Take into account how much of an bearing the pot or betting action is going to have on his stack, or tournament hopes. If he is generally a tight player and is willing to endanger more on the hand, then you can sensibly presume he is good. If he appears wanting to keep the pot tiny, then the pot is potentially yours for just a bet. Loose players are tougher to interpret in this instance, and it's more important for you to have a winning hand than to even bother trying to understand what their hole cards are.
Scrutinize how the betting and aggression changes AFTER the flop. Keep an eye on conviction that turns hesitation, or reverse. Practice guessing your opponent's hand before they turn it over. Again, you don't have to be in the hand, but you do have to observe the flop and follow the betting activity. Repeating this frequently will allow your evaluation of hole cards to become rather exact.