Can I just ask, why do you want to level up quickly? There's no use in it past level 17, which is the minimum required level for joining HWW - there are no other open games which require a higher level.
Having said that... I suppose you could join about a dozen games, and suicide all your starting troops into the neighbouring countries. That would work. But that would also ruin your k/d, and I assume you care about that since you're asking about levels.
My advice is, just play as you normally do. You'll level up, naturally, as you keep progressing through the game and play matches. This is a far more genuine and, may I say, fulfilling way of playing.
Don't get too attached to records or levels! Trust me, they don't mean much.
