Before going into battle, remember that one potion is always free to use - just make sure you select it.
If you get serious, splurge a little money on the character you most like using. It'll ensure you can continue to use her, even when she's not available to choose for those keeping things frugal.
Gold is important, definitely, but so is staying alive. Don't risk being killed just for the sake of a chest.
One easy tip you can use while playing is by telling the game that you would like to “Autobuy” all recommended items.
While playing, make sure you rush to the special items in the arena so that you have access to them first. You don’t want to give the enemies an advantage that you can have instead.
Before you choose a hero to play with, you can view each one by tapping on them first. When you’re ready to move on with the current selected character, tap on “Next.”