I never worry about trying to do well in the wishes and gold coin games. I just click along as I normally play, and I always win one of the lower prize levels (not gems but ranked somewhere around number 300). On the last gold coin game I did this starting right when the game started because I was already playing at the time. I ended up ranked where I always do. However, DD who just plays sporadically (maybe once a day for about ten minutes) and has very few buildings that give out coins ended up ranking high enough to win a gem. She started the coin game sometime in the afternoon of the day it started. And the winners on her leaderboard had much lower totals than on my leaderboard. So, I am going to try holding off on playing the wishes game just to see what happens. I think the wishes game is harder than the coin game, though, so it might not work as well.