There are a few ways to increase your chances of finding shiny Pokemon. In both Gen IV & V, you can use the Masuda Method to increase your chances to 1/1639 (0.06%) in Gen IV and 1/1366 (0.07%) in Gen V. In order to use the Masuda Method, you must breed a Pokemon from your game and a Pokemon from a different country together (Japanese Pokemon are the easiest to figure out of course).
In Black 2 and White 2 however, you can receive the item "Shiny Charm" if you complete the National Pokedex. This increases the chance of encountering or hatching a shiny Pokemon from 1/8192 (0.01%) to 1/2,731 (0.03%). If used in conjunction with the Masuda Method, it will be increased even further to 1/1024 (0.09%).
Though the easiest way to find a shiny is to RNG one. Doing it correctly will yield a shiny Pokemon every time. However it can be quite complex and isn't for everyone (and no, it isn't cheating). Trade Corner has a guide for basic RNGing and can be found
here.
I hope this wasn't too confusing.