Here is more a guide of if I had to start over what I would do.
At first, get use to doing a lot of clicking. You want to unlock 2 things as fast as you can, the first is the mage, and the second is the familiar. If you are like me, you want to do the bank, but trust me, start the familiar.
The familair does damage based off of the level you are own- so to put it more directly, it does % health damage. It kills all foes at the same rate. This quickly out classes your knights damage output until much higher levels. Once you have unlocked max familair, all your knight has to do is tank. Let the familair kill, its damage is stage based, not gold based.
The mage heals. Get the mage to the point he can max heal the knight over and over, and let him grind- walk away from the browser, put it in the background. Then, get to the point where you can do it to higher amounts. This stays effective until level 90. At that point, you will also have unlocked bank 3 and can quickly get your knights other stats way higher.
Max healing knight is the most important thing you can maintain. Once you get there, it is easy to maintain it and get extra gold for the other things you want to accomplish. It doesn't matter really what it is, since full heal with mage and a familair will beat you the game.