Quest Order

The primary quest line is strictly sequential: each one needs the previous one finished before it will start. It is also the gate on the map, so the quest order is the region order.

1. First Steps (Temple Woods)
2. Getting Started (Temple Woods) teaches water, gathering and crafting with Doric
3. Ratcatcher (Temple Woods) hands you over to Vannaka for combat
4. Rune Mysteries (Temple Woods) opens Runecrafting
5. Dragon Slayer ends on Velgar
6. Withering Heights (Fellhollow) ends on Imaru
7. Black Knight's Fortress (Dowdun Reach) ends on the Black Knight Titan
8. Icthlarin's Little Helper (Umbral Sands) ends on Fuzan
9. Regicide (Scorned Wilderness) ends on Kuldra

Secondary quests sit outside that chain and unlock as you progress through it. They are where new mechanics, features and recipes come from, so skipping them is the usual reason someone finds themselves underpowered three regions in. Tertiary quests only fire during a primary quest, and the first one appears during Icthlarin's Little Helper.