Poker is a game of skill over the long run, and you can improve your chances at success by signing up for training sites, networking with successful players, and brutally reviewing your play after every session. The best players also spend as much time studying the game as they do playing it, and this helps them win big at the tables.
Online poker differs from live poker in a few ways, but the basic principles of the game remain the same. The biggest difference is the lack of extra stimuli that can distract players. At a live table players can see their opponents and chat with them, as well as pick up on other nuances. Online, players only have their betting histories to rely on to make decisions.
Another difference is the speed of play. At a live table players can expect to see about 25-30 hands per hour, whereas online the number can be closer to 100. This increased pace can create frustration if you are dealt a dry spell, and you can end up making bad decisions as a result. The best players recognize this phenomenon and are able to use it to their advantage by playing marginal hands aggressively to maximize the profit they will make on average.
Limiting yourself to one table at a time is also an important step when playing online poker. There is a lot to process at a table, and the added stress of having other players around can lead to mistakes.