The challenges you have to complete are random each time new ones are chosen. I never got the one where I had to win 2 tournaments back to back.
But if you have trouble winning, I'd suggest playing Omaha. I had way more luck winning in that one, than in texas hold'em.
I also had a screenshot of the in-game cheatsheet open at all times, so I could easily check which hands I could get.
I also used this to check how strong my hand was.
Constantly going all in also seems to work for a lot of people. Good luck getting them guys.