Double or nothing poker tournaments are quite different to normal tournaments. They do not have a tiered prize structure, you either win double the original buy-in if you finish in the money or get nothing at all.
The most important attribute to have when playing the double or nothing tournaments is patience as players are usually playing pretty tight since there are more players who can cash in the tournament (half of the field). It is important to play a tight range of hands when you near the bubble, since regardless of chip stacks, whichever players make it in the money receive the same prize.
Once you have gotten a decent return on your money, you can work your way up to double or nothing SNGs that have bigger payouts. You’ll find Double or Nothing sit and go’s spread at most of the major online poker rooms.