The only "legit" way is to keep searching plains and desert biomes. There is no in-game way to determine exactly where they will spawn. If you don't mind cheating a little bit, there are a couple of other options...
1: You can re-create the world with the same seed in creative mode, then fly around and look for villages. They should appear in your main survival world in the same place.
2: Similar to the above, you can input the same seed and make the world superflat. This will make the villages themselves easier to spot, since there won't be terrain getting in the way or anything, but will result in a lot of false positives. Since superflat is all plains, there will be many villages here in locations that don't correspond to plains or desert biomes in your main world, and so there will be no village there.
3: Or, the most cheatiest of all, you can download the latest copy of AMIDST, input your world seed, and be shown a map that depicts the exact locations of each and every village in your world.
You can find them more commonly in the large biomes. The village-up mod has a village detector, but without mods there is nothing you can do except look. Npc villages also are found near pockets of forests and lakes in the plains biome.
type the command /seed write it down and open a new world, in creative and explore until you find a village, press F3 and write down your X
coords, go in your real world and go to those coords, BAM