To be competitive for junior level surveyor, take courses in trigonometry and surveying and, possibly, geodesy. A different route would be to look for Trimble survey-grade GPS training.
Most GIS Masters degrees are aimed at making you a GIS Manager. So you'll be wise to take some undergraduate physical geography or cartography course with it. Perhaps get an internship working alongside a GIS analyst.
To prepare for the capture of data: obviously, surveying is one. Natural sciences, like soils, agriculture, forestry, hydrography, hydrology, environmental monitoring .... plus today you should consider homeland security. Pick one that you know is in demand where you want to live.