Play way more than you should (and somehow don't go on a tilt), that's how.
I'll probably never get out of the crystal league. I don't have the dedication, and kind of lost my motivation to play a few weeks ago. Trying to regain it has been hard.
its easy, just get lucky with the league competitors, if they're lazy, you have a decent chance of winning. But just grind, don't do any cheeky strats, play normally and play a lot.
is there another league after that??