Masuda Method: it essentially involves you trading with a player that has a different language game than yours (e.g. French or Japanese), and breeding the foreign Pokemon with one of your own.
Commonly, people will trade for a foreign language Ditto, since you can breed a Ditto with almost anything bar legendaries. You can offer up a Ditto from your game as a trade for a different language Ditto and hope that someone with a different language game will see what you're doing (since they will benefit from the Ditto if their game is non-English).
Your usual shiny rate is 1/8192, while with the Masuda Method in Gen V, your shiny hatching rate will be increased to 1/1366.
Additionally, in B2W2, you can obtain the shiny charm from Professor Juniper for catching every single Pokemon in the national Pokedex bar event legendaries. This will increase your wild shiny encounter rate, but also your shiny rate when breeding, and the chances of breeding a shiny are now down from 1/1366 to 1/1024 with the charm.
Serebii - Pokedex completion