Early in the game it's good to summon some basic and advanced creatures so you can gain more dice each round.
These are great for using dice to greater effect. Spells tend to be stronger than similar abilities in creatures.
These are a great way to put your opponent at a disadvantage for 3 rounds.
Consider the auras available when deciding how to build your army. An aura which works well with your army can lead you to victory.
Mythic Creatures and Rituals
Mythic creatures are the most powerful creatures in the game however because it takes 5 sulphur to summon one, ensure you can survive until you can gain the benefit of the mythic creature.
Overall Strategy: Efficiency
Since your deck is the same as your opponent's, the defining characteristic of a winner is making the best use of your dice rolls, so find the most efficient moves to make with your available dice and cards. Particularly pay attention to what is the easiest and hardest mechanics to use in each deck type and plan accordingly.
This means that getting yourself more dice sooner (with creatures) is a top priority!
Red dice are more likely to give Sulphur than the blue dice, and Sulphur tends to be needed for more powerful effects.