I have been playing on Normal and been avoiding dragons until now (currently my Archer Inquisitor is Level 14). Combat hasn't been difficult so far, other than the Alexius fight. Today, I went to Crestwood and tried to take on the Northern Hunter, seeing as it is Level 13 and promptly got party-wiped.
I had:
Level 14 Archer Rogue Inquisitor
Level 13 Blackwall
Level 13 Varric (overlap, I know)
Level 13 Dorian (mostly fire magic)
I am not a RPG expert and I haven't paid much attention to crafting (it's confuddling to me). So, any advice on taking on my first dragon? The generic dragon fighting advice online hasn't been much help so far.
1st advice: wait a little more
I did it when I was level 15-16, it was tough, but I didn't know all the I knew now 
2nd advice: make sure you have chosen to upgrade your number of potions so you have 12, not 8. (it's in the war room, when you get enough points to choose new perks)
3rd advice: Bring Iron Bull as a reaver. The dialogue is awesome, but he also has some cool abilities.
4th advice: Bring Vivienne she is a knight enchanter and they have some really cool spells to use against dragons, just search the forum for a proper build (I spec'ed her correctly, but I haven't played in a month, so I don't remember, sorry
) You get close to the dragon and use her abilities, she does massive damage and the fight is over in a few minutes. Cold spells will help too, but nearly as efficient.
5th advice: Use the potions the reduces fire damage. Make sure you upgraded them too before going against this dragon.
6th adive: When the dragon flaps his wings, you got to move closer to the dragon, not away, to avoid damage. As soon as he stops, move away a little bit as he tends to use some aoe abilities to damage all your party.
7th advice: Attack from multiple fronts. Try to stay on the side of the dragon, one warrior to each side.
8th advice: since you play an archer, I'd bring 2 warriors to the party and Vivienne. That means, Iron Bull, Blackwall, Vivienne and you. Use Blackwall's abilities to reduce damage, don't care about doing damage, just make him the focus of the dragon attacks and have the other party members damage the beast. I hate archers in DA:I because they always go way to close to the ennemy and they are difficult to position correctly, unlike DA:O and DA2.
Hope that helps.