If you can follow up your combo with special move for maximum damage.
When you're not in the game set a bot to defend your base. Not only he'll protect what you got but they’ll also generate gold for you overtime.
Keep in mind that the higher rarity bots you use, the more gold they’ll generate.
You'll be able to get by with attack only strategy on lower levels but if you really want to proceed you need to master defensive maneuvers as well.
Watch out for retaliation moves once your combo is done for. Get your shields up. Also watch out for transformation of your enemy. Once they start to transform backdash from him and get that block up immediatly.