Chose wisely your creatures, and be very careful in their use.

Once a creature get its max xp, it's almost useless to give it more winnings.
Don't regret to sacrifice some of your best monster: the reward may be very interesting, and it could give you the opportunity to evolve a better creature.

Strong creatures and fine tuned rituals, make you strong. Still. it could be not enough for the heads contest.
It's a really hard competition, And not ever brute force is the key.
You must use your brain, try to get the better bonus by every tricks available to you.

And remember...... find good and strong friends.... they will help very much.
Good cohoperation is the real key for victory.