It's kind of hard to give advice without knowing your preferences, and what levels you struggle with, RSIK4. For instance - when I was inexperienced, I found it easier to upgrade Quen and rolling to the max - something I no longer do in the beginning.
Currently, in the early on, I mostly use the alchemy tree to maximize damage, but I'm uncertain whether you can complete the initial stages well enough to handle having so little HP.
Generally, though, it is very helpful to drink potions after the 5th level, and to use the Circles of Power. It is also extremely useful to upgrade bombs twice in the alchemy tree. They really pack a punch after that. You can then easily defeat harpies and all the other agile monsters. The support of the dwarf is obligatory, you should have him at your side whenever possible. Don't hire anyone else, ever.
So what else is worth mentioning? The golems, you swing the heavy attack before their face, so one of them starts charging, and then time the roll to backstab it, rinse and repeat while not forgetting to keep your quen up. Do the same with fire elementals, but not before destroying the gargoyles with upgraded grapeshots.
Let me know if any of that helps, buddy.