Yep. starwarsmenzel is exactly right. This concept is known as preloading. If you can't 3 star a planet, just load it with GP up to about 10 mil buffer from 1 star to give yourself a leg up in the next round. Also, don't underestimate doing ops. Each op gets up a min 10 million GP, and the more of them you complete in a planet, the better bonuses you get to complete combat missions, which in turn give you more GP. I'd suggest putting a game plan together with your guild and find out which characters need to be worked on (relic'd) to give you the best bang for your buck in ROTE. My guild posts a volunteer list of characters needed to help us complete more ops in more planets. There are plenty of youtube videos out there that explain this concept. I think you should be able to get 18-20 stars with implementing a couple changes. Great question!