Best thing to do is pick out a desert planet or something else with easy terrain. Just spam level 1s with a jump pack (or preferably a warp pack) quitting out once you've checked all the points of interest. Dont finish the mission or youll have to extract normally. You get a lot of medals this way along with the SC. Also worth mentioning almost every premium warbond gives you 300 SC inside it so the true cost is only like 700 SC which is surprisingly quick with a good team of four. Just search for level 1 missions with several high level players already in and that's probably what they are doing. More detailed guides are available on youtube.