Well you need to grind a bit to unlock stuff and get the gold but you can get the option to reroll and then lancet and laurel are the main things to being practically unkillable with enough leveling.
But for early level seriously just upgrade whip and get the heart. You now heal and do near constant damage. And then get garlic and just work on maxing out any item one at a time. And you will keep going until the waves become bullshit. Keep doing until you literally grind ypur way to buying your way into the end game.