https://www.gamespot.com/articles/el.../1100-6501255/
See above, it is easily doable at a low level, you just need a bleed wep, as the bleed procs are based of the mobs total HP not your dmg so you can kill it pretty quickly. There is also a way to glitch this, by running back to the site of grace and resetting before the dragon dies and you get the runes and the dragon never dies, I have never tired this but heard about it.
I would say, the Millicent and Rani quest lines are the best ones to follow, again YouTube is your friend if you get stuck. The Alexander one is a must for the end rewards, you will need youtube for sure for this, as you need to make a potion and hit him with it a few times on your second encounter, again no idea how you would figure this out.