How can I find Villages in my world?

As far as an in-game (i.e. "not cheating") solution, the only real guidance I have found is this line from the Minecraft Wiki:

They only occur in the plains or desert biomes.

So that's where you should limit your searching to, probably around the edges of the deserts as this image shows:

Another alternative listed in the "Finding NPC Villages" section of the wiki involves making a superflat version of your map (using your map seed), then flying around in creative mode. As noted, however, this can give you many false positives (i.e. villages that spawn on the superflat map that wouldn't spawn on the normal map due to the presence of a non-flat biome).

Options outside of the game, as listed in this answer about finding strongholds, would be to use cartography programs to inspect your map for tell-tale blocks that you might see in villages. Good indicators might be:

• Bookshelves or crafting tables, which show up in village libraries.
• Pressure plates, which are used to make tables in houses and shops.
• Furnaces or iron bars, which show up in village forges.
• Many rows of wheat.