Tournaments vs. Cash Games
If you're a successful cash game player, you've probably already contemplated making the move to tournaments online. Sure, cash games can be extremely profitable, especially at mid to higher stakes levels, but the only problem is that each and every dollar that you win requires an almost same size investment on your part. If you're a solid winning cash player the rewards can be huge but so can the variance and swings in your roll.
On the other hand, when you are playing in tournaments (and I'm talking about high buy-in Guaranteed prize-pool MTTs here, available at every online poker room on a weekly/monthly basis) your initial investment is infinitely smaller than your potential winnings. This is what brings most tourney players to the tables, and one big score can really set you up for the year or if you are exceptionally lucky perhaps even for life (like in the case of winning the WSOP ME). I use the word lucky in tournaments because the luck element in tournaments is definitely far greater due to the increasing blind levels, so players are much more likely to make mistakes, and in big MTTs, that means you will have to get lucky, win lots of coin flips in order to run deep in the vent and outlast a really large field.
If you're primarily an online cash game player, but thinking about playing more tournaments, be careful though: the fact that you're good at cash games doesn't guarantee that you'll be equally successful in tournaments. While they're played by the same rules and with the exact same 52-card deck, cash games and tournaments can be very different in places.
I'm not trying to overstate the obvious here, but the first thing you need to get used to in tournament poker is that your stack is finite. This is the concept from which most of the differences between cash games and tournaments stem. In cash game poker, your stack is a mere weapon. It is not directly connected to your survival at the table (if you get felted, you can always re-deposit and get rolling again). In tournaments, besides being a weapon and a tool that will make it possible for you to amass more chips, your stack is also your life-blood. As it gets shorter and shorter, your options grow fewer and fewer too. When you lose your last chip, your tournament life is over: your buy-in is lost and there's nothing in the world you can do to recover it. You've met tournament failure.
Due to this fact, the odds associated with all-ins suffer a modification in tournament poker. In a cash game, going all-in on a coin-flip may carry a marginal EV+, but that is no longer the case in a tournament. Shoving all-in on a coin-flip there should be a well calculated yet desperate move there, one that takes the fold equity into account and one that needs to be avoided if possible since your tournament life is on the line. In tournaments the fewer times you go all in the better since the less chance there is of you busting out.
Your playing style needs to be more flexible too. You may find that good old solid ABC poker is all you need at certain cash tables to give you an edge over your opponents. In other instances, being loose aggressive may be the way to go. In tournament poker, you need to learn to adapt your style on the fly, to the ever-changing bunch of opponents you'll be going up against as well as to the continuously escalating blinds.
In general terms: you start out tight and gradually loosen up till you turn into a genuine maniac during the heads-up stage (provided you make it all the way). Taking advantage of your opponents on the bubble is another of the basic elements involved in successful tournament poker. During this phase of the tournament so many players will be tightening up so they don't bust out and make the money, and you want to exploit them at every opportunity you sense weakness. Learning about the importance of fold equity and learning to steal and to re-steal blinds are also extremely important for a good tourney player.
Don't forget though that at the end of the day, poker is poker, and the basic strategy principles that work well in cash game poker should work just as well at the tournament tables too, despite the subtle differences listed above. More then anything else though, how you should approach a game, whether it's a cash game or poker tournament, will largely depend on the quality of your opponents. At the micro stakes, the games are full of “fish” or donkeys, so it shouldn't be very difficult winning their money if you stick to good game fundamentals.