Level doesn't mean much, like right now I'm a level 20 and all the cards in my deck are level 1.
To earn money, play in the tourament, a niffty trick to doing well is to level your cards during the torament because you get higher points and thus, a higher rank that way. The higher the rank the more clintz you win. I say never turn down a challenge, even when you lose your cards gain exp and you gain some clintz. Also, notice the people with evo in their names, they're good people to face to level up with, check "master's tips" for more on that subject.
The Urban Rivals team is made by lovers of all kind of Collectibles Cards Games and Trading Cards Games like: Magic the Gathering, Dominion, Vampire, Yu-Gi-Oh!, Pokemon, Wakfu TCG, Assassin Creed Recollection, Shadow Era, Kard Kombat and Might & Magic Duel of Champions.