To answer many most commonly asked questions, I've compiled this basic guide for all classes in Ether Saga Online. Here you will find screenshots of them all, along with the most used builds, recommended crafting vocations, and pet advice.

Conjurer Guide 

Conjurer is an offensive caster class. They can also cast damage-increasing buffs. Their attacks are intelligence based. They wear light armor and have lower defense than most other classes.

Build
Most Common Build:
Pyra/Unda: Conjurer class skills are based on Pyra and Unda. Each point you put in Pyra gives you +3 intelligence and makes your Pyra-based skills more effective. Unda gives you +20 maximum health points and assists Unda-based skills.

An Alternate Build:
Pyra/Widu: This build trades the +20 HP and the boost for Unda skills Unda would have given you for an additional point of intelligence and increased evasion. Not recommended for PvP.

Recommended Crafting Vocations
Conjurers need Arcanecraft to create their own armor, and Hunting to gather the materials for it.


Pets
A commonly asked question is "What pet is best for a conjurer?"
Keep in mind, pets have random attributes when caught. There is no best pet by name. For Fusion: watch for a Fierce temperament with high HP growth and nice fusion bonuses (hp, def, evasion, resistance). You also want bonuses to Pyra/Unda affinity, Intellect, and Accuracy. For Summoning: Cautious temperament with high INT growth. Alternatively, you might choose a Bright or Normal pet for summoning, due to its healing ability. (Bright pets can also buff.)

Dragoon Guide 

Melee attacker and/or tank class. Wears heavy armor and wields a lance.

Builds
PVE/Instances:
Erda/Unda: Your skills are Erda affinity, and Erda gives you +1 Strength and +1 Defense per point you put in it. Unda boosts maximum hit points, and HP/MP recovery rate.

Damage Per Second Build:
Pyra/Erda: While most of your skills are Erda affinity, Pyra boosts the effectiveness of skills.

Recommended Crafting Vocations
Dragoons need Guardian Forging to make their own gear, and Mining to gather materials for it.

Pets
A commonly asked question is "What's the best pet for a dragoon?" Keep in mind, pets have random attributes when caught. There is no best pet by name, you have to pay attention to their attributes. For a Fusion pet, you want: Fierce temperament, good HP growth, and bonuses to Unda affinity, and things like hp, defense, evasion, resistance. For a Summon pet, you want: Bright temperament, for healing, high Int gain, good hp.

Mystic Guide 

Defensive spellcaster. Can heal and cast defensive buffs. Wears light armor and equips staves.

Build
Most of your skills are Unda affinity, and Unda affects your maximum HP. No matter what, you want points in Unda.

Most Common Build:
Unda/Pyra
That's 5 points in each every ten levels. One typical way to do this is to put 3 Unda, 2 Pyra at level five, then 2 Unda, 3 Pyra at level ten, and so on, alternating. Pyra is chosen because of the +3 intelligence bonus it gives, thus the increase in effectiveness of skills.

Recommended Crafting Vocations
Mystics need need Arcanecraft to create their own armor, and Hunting to gather the materials for it. If you want to make your own potions, you need Cooking. You can only have two vocations at once, although you can forget one at will. Unfortunately you then lose any money you spent on recipes because you forget them as well.

Pets
A commonly asked question is "What pet is best for a mystic?" Keep in mind, pets have random attributes when caught. There is no best pet by name, you have to pay attention to their attributes. Fusion pet: you want a Fierce temperament, with high hp growth and bonuses to mana, int, and unda affinity. Summoning pet: you want a Bright or Normal temperament for the heal skill.

Ranger Guide 

Build
Most Common:
Widu/Unda: these are the two affinities that directly affect ranger skills. Widu increases intelligence and evasion. Unda increases your maximum HP and your HP/MP recovery rate. Assign your affinities as 5/5 every ten levels, by alternating 3 Widu/2 Unda and 2 Widu/3 Unda every fifth level.

Recommended Crafting Vocations
To make their own gear, Rangers need Scout Crafting, and Woodcutting to gather materials for it.

Pets
A commonly asked question is "What pet is best for a Ranger?" Keep in mind, pets have random attributes when caught. There is no best pet by name, though you might find a combat pet with a ranged attack, such as the Tigero Ranger, suits your ranged play style best, staying out of harm's way by still helping in battle. In a summoned pet, you may want a Bright temperament, for its healing ability. For a Fusion pet: Fierce temperament, with bonuses to Unda affinity/evasion/accuracy.

Rogue Guide 

Builds
Common Build:
Oora/Widu: All your skills, save one, are Oora affinity, so this affinity is a must in any successful Rogue build. Widu is a favored second affinity because it increases resilience (dodge), at a rate of 1 per every 5 points in Widu. it also gives a little boost to intelligence which increases the effectiveness of skills.

Another Popular Build:
Oora/Erda: Erda gives increased defense at a rate of 1 per 1 point in Erda. It also slightly raises accuracy and increases Critcast damage.

Recommended Crafting Vocations
To make their own gear, Rogues need Scout Crafting, and Woodcutting to gather materials for it.

Pets
A commonly asked question is "What pet is best for a Rogue?" Keep in mind, pets have random attributes when caught. Ideally, you'd want a fusion pet with bonuses to Oora affinity, accuracy, and evasion. Summoning pet: you want a Bright or Normal temperament for the heal skill.

Shaman Guide 

Spellcaster/tank. Uses healing magic spells and status effects to aid as a secondary tank class. Wears heavy armor and wields hammers.

Builds
Common Build:
Widu/Erda: Most of your skills are based on Widu, and Erda gives you +1 Strength and +1 Defense per point you put in it.

Recommended Crafting Skills
Shamans need Guardian Forging to make their own gear, and Mining to gather materials for it.

Pets
A commonly asked question is "What pet is best for a shaman?" Keep in mind, pets have random attributes when caught. There is no best pet by name, you have to pay attention to their attributes. For Fusion: a pet with fierce temperament, high HP, with good bonuses for your build. For summoning, for group support and healing: a pet with bright temperament.