Using a water index such as MNDWI (for images with SWIR band) or NDWI (for images without SWIR band) to highlight water features, and then separating wetland form other features with proper threshold values.
Multidate imagery that captures the phenological differences between the upland and wetland features is an effective technique. Three dates (spring, summer, fall) is a good generic rule (such is used by many national US projects) for general mapping, however a more careful selection tuned to feature phenology will likely provide better discrimination on a more local scale. For prairie potholes in particular, I have had excellent success using two dates: a wet year and a dry year.