I would still-hunt if you have not yet identified an obvious food source. If you have several days to hunt put out trails of corn in stalkable areas.
As has been said, you will often hear them before seeing them.Like Gregg said, if you see some get the wind right and close the distance. I've successfully stalked them in wide open pasture by moving when they move and closing the distance quickly when possible.
If there are feeders or a known food source sit in the evenings.
Good luck.