Don't worry too much about earning extra XP from actions, your first priority is winning, or you will lose all gains made anyway. You don't need a ton of gold, and only the treasure chests are worth going out of your way for. Leave most coins on the floor, unless they literally fall into your lap along the way, or you have a convenient moment of peace to play that Loot card. Only once you're in the last room, with most enemies under control, and confident of victory, you can afford to relax a bit and start grabbing coins and playing cards for maximum XP. Feel free to let the last guy live an extra turn while you grab what you can.