A good online poker player always takes down notes. The notes on other players will serve him well when he meets the same players in the future. Note down whether a play is tight or loose, passive or aggressive. Another thing that you should observe is whether a player defends their blinds or not. You should also note if a player is either winning or losing. Lastly, note if the player likes to bluff, or plays it straightforward. These are just a few things you could observe about other players.