2. I didn't craft much so don't know about materials, but if you're going for all achievements on one run, you'll want to save Elfroot and Blood Lotus (30 of each) to upgrade Skyhold's garden (allowing you to grow 6 herbs at a time instead of the initial 2, allowing you to upgrade your potions quicker) I generally sell all my "valuables" unless they come with flavour text or are creature research items, except Spider Ichor and Dwarven things, as they are used in quests/requisitions.
3. Personally I stayed in Hinterlands as much as I could, I don't like moving on with main plot until I finish all available sub-plots. This results in you being over-levelled for the other regions but I enjoyed that. Your preference.
Other tips I'd give:
- Keep at least one warrior and one rogue in your party if you like full exploration. Warriors can knock down certain walls to secret areas or create shortcuts, and rogues can unlock doors to loot rooms.
- Your health recovery in battle comes from the use of armor, shields, and health potions. Look into obtaining+upgrading regenerative potions and healing mist tonic. There's also an Inquisition perk for increasing the amount of potions each character can hold.
- On Nightmare mode, if a main plot mission recommends you to be "level 4 to 7", you'll want to go into it being level 7 or higher.
- A mage's Dispel ability can negate spawn points during Rift battles. Inbetween waves, the Rift shoots out green energy to points on the ground; cast your Dispel at these spots to cancel that spawn point, meaning you deal with fewer enemies.
- If you play a mage, I personally recommend choosing to be a Knight-Enchanter. You're able to deal more damage physically whilst it automatically regenerates your barrier, and makes the barriers you cast on others last longer. It has been the biggest help during dragon fights.
- Dragon fights are currently bugged; the achievement counter may not update after killing a dragon. Comments on TA say you can reload a save for any non-glitched dragon fight, kill it, and it'll count again to your counter. I've also read that you can still fight the dragons post-game, so it may be worth doing it then when you're stronger / able to turn the difficulty down.
- I believe that Agents you obtain count as 'points' for the Inquisition perk category they get listed in, allowing you to access the 'higher' perks earlier on (such as ones that say "You must have 4 points in Connections to obtain this perk"), so if this is the case, you should collect as many Agents as you can early on. See the solutions on the Agent solution for more info.
- Fast-travelling to a camp automatically heals your party, I think?
- Some operations on the war table at Haven are missable as not all of them are available at Skyhold.
- Vivienne, Blackwall, and Iron Bull are the only missable companions, I believe, so you may want to read on how to obtain them specifically.
- Every time you visit your base, hand in creature research items you've collected for damage bonuses against that creature type.
- Though there are conflicting bits of info on this, apparently when a companion's card (appears when selecting your party) changes its art permanently, this indicates this character is now your friend/loyal.
- For lots of easy XP, grab yourself the Codex perks early on to increase the amount of XP each codex gets you. Walking into Val Royuex for the first time and inspecting everything is enough to go up half a level.
There's also perks for increased XP from killing enemies and research items handed over, but if you're going for all the achievements and like a bit of bonus exploration, you'll get to Level 20 and still have dozens of quests left to do.