Vocations

You chose your class at a recruiter before you left Rookgaard, and that choice is permanent — there is no way to change it, so a second class means a second character. Your health, mana, movement speed, regeneration, capacity and the ceiling on your crafting skills are all set by that class and your level. There are six: Knight, Archer, Sorcerer, Druid, Necromancer and Templar.

Spells

You can learn spells by talking to your vocation's teachers. Start by asking them what spells are available. Most spells are bought; the ones your promotion earns you are handed over on the spot. List of all spells is available here. Say !spells in-game to see your spells.
At level 20 ask your class master for promotion. It costs 5,000 gold and gives your class its full identity - a Necromancer's ritual to raise a Bone Guardian, an Archer's traps, a Knight's Rage, a Templar's holy words. Once you buy the promotion, you will be granted a suite of spells related to your class identity.

Supplies

All supplies can be bought from vendors, and you definitely shouldn't sleep on them - try having at least some life potions on you at all times.
Potions can be brewed using your Alchemy skill, Runes can be crafted using your Runemaking skill - those crafting skills are very useful even at the lowest levels.
As an Archer remember to use your "Spectral Valley" spell to save up on ammunition at low levels.

Triggers

On Kinara your weapon hits can proc reaction skills. Once a reaction skill is procced, you have 4 seconds to use it.
Can Block! - say block! and every hit you take for the next half second is fully blocked; the first one blocked also gives you some free mana (you gain it even if that hit was already down to 0 damage). Damage you are already taking over time, and the field you are standing in, still get through. This one never procs while you hold a bow, crossbow or throwing weapon - those get a better chance at Steady! instead.
Empowered! - say exori amp to use your empowered strike (available from level 12), which effect depends on the weapon in your hand.
Third trigger depends on your weapon, say strike! to activate it:

Steady! (bow/crossbow: your next shot lands for maximum damage).
Focused! (wand/rod: your next wand/rod hit deals far more damage).
Sanguine! (sceptre: your next shot hits harder and heals your Bone Guardian, or you when no guardian is out).
Can Parry! (melee weapon: block incoming hit and strike back).

Once you use the reaction skills it will work only for a short moment, so try timing it just before your next attack (or just before enemy attack in case of parry).

Where to go, what to do?

When you leave Rookgaard the ferryman at the shore asks which city is to be your home and sets you down in its temple. There you can buy basic spells, possibly some small life potions and your class-specific weapon.
Don't forget to store items you don't need in your personal depot and deposit money to the bank.
The most efficient way to progress is to embrace the journey and explore the world around you.
Pick Thais or Carlin if you're a complete beginner, then venture out looking for creatures to kill or quests to complete. Remember, unlocking bestiary entries and completing quests will reward you greatly.
You can check what kind of quipment you can obtain from quests, creatures or vendors and slowly work towards upgrading your gear, especially the weapon.

Settings & tools

• Set up your hotkeys: potions , spell incantations “send automatically”, and your block!, strike! and exori amp(Empowered Strike) should always be on your hotkeys!
• Your mouse wheel triggers hotkeys too — scroll up acts as pressing F6, scroll down as pressing F8 and clicking the wheel fires F7. Holding Shift or Ctrl allows you to assign up to 9 hotkeys on just your mouse wheel. Try both the F-keys and the wheel and see which feels better for you.

Stuck? Ask on Discord.