The following skills are a must.
Proficient in QGIS and ESRI ArcGIS
Map packages, map books
Experience making maps in Google Earth and Google Maps, working with KML and KMZ files
Converting shapefiles to KMZ and Google Earth overlays etc
Experience working with rasters, high resolution imagery such as rapid eye, world imagery, digital globe, GeoEye etc, swisstopo, DEM and experience using Open Street map
Georeferencing hard maps , and digitizing
Importing and integrating CAD data to GIS.