A lot of people are currently trying to play online poker as a full-time career, or at the very least are serious about making a steady monthly income from poker. For many that means grinding out eight hours a day multi-tabling in cash games (playing several tables simultaneously) while others focus exclusively on tournaments. Let's address two important questions here. Should you specialize as an online poker player and only play one variant of poker? Are players with a specific style (a rock say) or specific skills (analytical players who can calculate table odds quickly) better suited to one variant of poker as opposed to any other?
A common mistake amongst novice poker players is the idea that if you`re good at one type of poker game you`re naturally good at all the others, and an even more common mistake is the feeling that one should be good at all types of poker in order to make a living playing the game. In my opinion one requires a different skill set, a completely different strategy, and a different approach in general if you want to succeed in tournament play as opposed to cash games. Furthermore, there is another divergence between successful limit poker play and thriving in pot limit or no limit cash games.
When you are first starting out in poker it is important to try both tournaments and cash games and to expose yourself to limit, pot limit, and no limit action. You need to see where you are strongest, and you have to be brutally honest with yourself. To play pot limit poker requires a high level of risk tolerance, and if you're a super-aggressive maniac who will bet fearlessly it sure helps. A player like Sam Farha is well known as one of the best pot limit Omaha players in the world, and to play pot limit well you cannot be subtle or tight. Maybe you're not that type of poker player - most of us, if we're honest, are not.
By contrast, one of the best limit hold'em players is Jennifer Harman, who is a very shrewd and patient player. She likes to wait for situations where the odds are in her favor and plays very solid, non-Sam Farha poker. Sam doesn't have the patience for limit games but Jennifer does, and the reason they're both able to make a living from poker is that they play to their strengths and avoid those situations where they're giving up an edge before they sit down.
My advice is to specialize in either tournaments or cash games when you start out, and by that I mean focus your attention on mastering one format. In terms of money management it is also far easier to try and improve your game by playing a lot of single-table tournaments. The fluctuations to your bankroll are far less intense. If you attack multi-table tournaments you run the risk of not cashing regularly enough to keep your head above water. You could of course hit that one big score that will propel your bankroll to new heights, but it is obviously a very risky strategy. If you play Sit 'N Go tournaments it is an excellent blend of risk and reward, but that's just my personal preference.
For example: You have $500 that you want to deposit into a poker room and your plan is to learn and become a stronger player, and additionally you would like to show an eventual net profit. You will be much better off playing in 20 $20+$2 Sit `N Gos than in taking your $500 to $3/$6 limit tables, where you will play 5 sessions with $100 each time. The standard of play is probably very similar but you will get more exposure and gain more experience playing tournament poker. You also learn good habits in tournament poker. It is very tough to win tournaments if you consistently chase hands when you know you're behind. However, in no-limit cash games this strategy often pays very big dividends.
This key difference is fundamental to understanding what I meant earlier about different formats suiting different player profiles. In no-limit cash games you don't mind gambling when you're behind provided you have the bankroll and stomach for the risk. You actually should want to build up huge pots when you are on a drawing hand, and if you lose it is no problem to re-buy, and the money you lost is still in play and very much up for grabs. You can easily lose $500 in no-limit then re-buy and end up winning $1500 for a net profit. But in tournament poker you may only get to chase once, because if you miss and all your chips are in the middle the tournament is over for good. You never get the chance to play for those chips again, they're no longer in circulation as far as you're concerned.
It is not surprising that relatively few poker pros are both good tournament players and good cash game players. The list of those players who can do both well is a short one: Phil Ivey, Barry Greenstein, Daniel Negreanu and Doyle Brunson in his prime are names that come to mind. But the list of those who cannot do both is extensive. Someone like Chip Reese is renowned as one of the best cash game players of all time, and he is a great mixed game player as well, but his record in tournaments is comparatively hopeless. Stu Ungar donated millions in cash games but today is remembered as the greatest tournament player who ever lived. Phil Hellmuth has a terrific tournament record but you will never see him sitting down in the big cash games (unless it's a gimmicky game for TV) simply because he might be a loud-mouthed, obnoxious narcissist but he is no-one's fool.
If you are a naturally tight player who is patient and you're not really a gambler you are going to fare well at medium limit poker cash games and you will also be suited to single-table SNG tournaments. You will, however, struggle in short-handed games especially if they are pot limit or no limit, and you will also find yourself never cashing in big multi-table tournaments, and it will be inexplicable to you as to why this is. It's pretty simple to explain, though. You have to be far more aggressive and loose in big fields and in short-handed games with big pots. If you are a born gambler and you have the cash resources to survive those roller-coaster fluctuations, and those long months when you keep busting out early, then this is your type of poker. It's not recommended for grinders or novices, however!