This may not make intuitive sense to everyone, but the site and type of tournaments you play has a lot more to do with consistent success than you may think. In the US, it is no coincidence that the best tournament players are consistently playing at Ultimate Bet, Stars, Full Tilt and Bodog. Granted these tournaments have strong guarantees for higher buyin tournaments, but they got there for a reason. They are great tournament sites.
What makes a great tournament site? I think there are 3 key factors; tournament structure, number of players and rebuy options. First tournament structure is critical, a good player wants an adequate level of chips and sufficiently slow structure so that they can get some play with their chips and try to build a stack while the blinds are low. Many sites on the web, like the Prima Network and others, have such fast blind increases that their tournaments are paramount to gambling. Good players do not want to simply chalk up their entry fee strictly to chance. Any tournament takes a certain amount of luck to win, but skill is more important to consistent cashing and long-term success.
Ultimate Bet and Bodog have the best structures for sites with a base level of players. Bugsy's Club has probably the best structure on the net with every tournament starting with 10,000 chips, but they have so few players that prize pools are rarely very large.
That is a good lead in for the second factor, number of players. The more players in a tournament, the bigger the prize pools. Several of the big sites have $200 buyin tournaments on the weekend with in excess of 1,000 players. Now there is a trade-off here. I like to play tournaments with between 150 and 400 players. Less than 150 and the prize pool is not large enough to make it worth the time. However, above 400 and the luck factor becomes to great a factor in getting to the final table. While both payout to 10% of entrants, most of the money is given to those at the final table. In tournaments with more than 400 players, you need more of your good hands to hold up and you need the luck to win a lot more races to make the final table.
At a site like Stars this can be a real problem, especially if you are playing in the $5-$30 size range. These tournaments almost always have more than 1,000 entrants and you will grind it out forever before making a big score. This can be so frustrating that it can lead to sloppy play or overall disappointment with the game. At Stars, I try to limit my play to the $20 and $30 rebuys or tourneys, larger buy-in tourneys and the capped size tourneys (180 SNGs and 360 max tourneys)
If you play lower denomination tourneys, I highly suggest that you look at UB. They offer a lot of lower buyin tourneys and the number of entrants is usually 100-300 people.
The third factor is rebuy offerings. One thing you will note is that good players like to play rebuy tournaments. Rebuy tournaments give a good player the best chance to win because they can start with a big stack. At most sites you can rebuy immediately to double your stack. Then if you are able catch some cards during the rebuy period, you likely will double your doubled stack, so you might have 6,000 chips (versus 1,500 in a normal tournament). Then you can addon for 2,000 more chips at the first break. So now you have 8,000 chips and the blind levels are likely in the 75/150 range. Your M is 35 (chips divided by blinds/antes) and you have a lot of room to play pots and try to build your stack. That is why good players play rebuys.
One of the little known benefits of playing rebuys at UB and Absolute Poker is that they allow a double rebuy and double addon -- which further increases the stack size to multiply the benefits discussed. If you wait until the tourney starts at UB, then when you click the rebuy option it asks if you want a single or double rebuy. If you double rebuy, you end up with 4,500 starting chips. Let's say you build that up to 7,000 chips by the first break, then you do a double add on for another 3,000 chips. Now you have 10,000 chips and UB has one of the slowest blind structures, so the blinds after the first break are still only 50/100 after the first break. Your M in that example is 66 -- that is a big stack relative to the blinds.
I love to play the $30 rebuy at UB as the prize pool is very large. Yes, I end up buying in for at least $150 but the chance of cashing is greatly increased with the stack size you can usually build during the first hour. They also have $2, $5, $10 and $20 rebuy tourneys.