One of the very first things I suggest that you do is progress through the early stages of the Adventure mode. This will give you quite a few good resources and Rubies from the very beginning, and trust me - you will make great use of them! You should go ahead and try to do as many stages as you can, so you can level up your Elunes (heroes) and claim the fourty-five Rubies that you get for the first completion of the stage. These are going to be super useful when you want to summon more Elunes, so don't waste them! Save them up!