I'm a new-ish player, having started about the same time the Halloween Fiesta event did. I'm making decent progress, at least based on my rankings in the events. I hit around 19,000 in that one, about 9,000 in Abyss, and I'm hovering in the 4,000 range for the current one. Unfortunately, I'm hitting what seems to be a familiar wall. I have around 20-30 4* that I want to trade in, but no takers.
Also, does anyone know if there's a way to change your gamer name? I used my real name, which didn't matter when I was more into single-player games like Tiny Tower, but now that I'm in multiplayer games, I'd rather make it something more private.