ArcPy has a function called: ListFields (dataset, {wild_card}, {field_type}) where all you are required to pass is the dataset. The wild card and field type are limiters that can help slim down the results.
sdeFile = r"c:\temp\connectionFile.sde"
fc = sdeFile + os.sep + "myFeatClass"
fields = arcpy.ListFields(fc)
for field in fields:
print field.name
The code returns a field object from which you can access a whole set of properties. This method is preferred when examining spatial data because it provides the data in a format that the Arc system can read and understand. Enjoy