The Best Strategies for all Classes. Feel free to add your own comment from experience.
No these are not in the order in which you unlock them, but if you would like to add it feel free.
The wizard is a long range class which uses Staffs, Robes and Spells. A good class to start out when you are new to the game. He has a high chance to get soulbound damage and if his spell is used effectively, he can practically decimate any enemy. It is the best pot-farming class. If you can get the dexterity up high and a strong staff you can tank some enemies.
The priest is a long range class which uses Wands, Robes and Tomes. The priest class is one of the few classes that allow you to heal yourself/others. Although it has extremely low drop rate chances it can tank anything with its healing ability. The priest is an invaluable character in dungeons such as the Abyss of Demons and The Shatters due to the healing ability. Just watch out for those quiet stars and don't get too cocky!
The rogue is a medium range class which uses Daggers, Leather Amour and Cloaks. Rogues are more for the experienced as you need to get used to his ability. He is more of a solitary class as he does not have an ability that helps others. When used effectively it can solo almost anything. Be careful, though, when fighting with other players. the monsters will still shoot them, which may hit you instead!
The warrior is a short range class which uses Swords, Heavy Armour and Helms. Warriors are the first Melee class that you can unlock. It has an extremely useful ability which can be used to buff others or rushing. With high armor it can tank most enemies. He is the introductory class to the Melees. Warriors are awesome at tanking dungeons. Their speed buff can help them rush past rooms filled with deadly monsters. Most effective when rushing the woodland labyrinth.
The archer class is one of the most useful classes. It can use the doom bow which does massive damage to all foes. The quiver or ability is most effective when the target is close or charging.The archer uses a light armor which is less effective at defending than heavy armor.
The knight is a short range class which uses Swords, Heavy Armor and Shields. With an extremely useful ability, this class can stun any enemy (causes enemies to be unable to attack). It has the highest defence in the game and can tank almost anything that comes in its way. When fighting Oryx the Mad God 2, a good tip is to circle him counter clockwise. This way, if you get confused, you will not run straight into Oryx the Mad God 2 and eat his 3,000 HP shotgun. Once you're close enough, quickly stun to again avoid an unpleasant trip to Oryx's 3,000 HP shotgun. if it works, blast away, but remember to either keep him stunned or else get out! Also, in the tomb of the ancients, be very careful when going in to stun Bes in his rage phase. If you have a laggy computer or are not quick enough with the stun, he will fire his armor-breaking shield that can instantly kill you. If you are 8/8, lucky, and fast with the nexus button, however, you might be able to escape to Nexus with about 40 hp left.
The necromancer is a long-range class that uses Staffs, Skulls, and Robes. Your ability sucks life from the enemy, so use it when you have low HP. Since the necromancer's Skull takes a certain amount of damage from any number of monsters and adds the combined hp damage to equal the amount of hp you and your friends heal, it is ideal to clump monsters together and then suck away their life. especially useful in Lord Ruthven's bat phase. The record a skull has ever healed is 1,315 hp, when there was a group of about 20 Demons clumped together in an Abyss of Demons. this is enough to get you and everyone around you to full HP. The maximum amount of HP a character can have is 1,010.
Buffed a while back, the mystic, which can be used for duping, has become fairly balanced. Her orb has the stasis ability (which turns enemies nearby into stone statues which are technically out of the game for a short period of time) can be useful when fighting bosses with minions that only get in the way (i.e, Lord of the Lost Lands). It is also useful when fighting constructs; they heal each other in a pattern. If you can stasis one or two and then quickly kill the one that doesn't heal, you will mess up their healing pattern and be able to kill them all. As well, the curse effect allows nearby enemies to take 1.5x damage. Note: a knight with the Demon Blade or maxed attack and dexterity can kill constructs just as fast, if not quicker, while losing less HP.
The ninja is a rather unbalanced class. It does not have that much defense, attack power, or range, and the Shuriken ability requires a lot of practice to aim well and uses a lot of MP. To practice aiming, look at the Best Class Strategies#Archer's tip. The shuriken also gives the effect Speedy when the spacebar is held, which can be useful for Wine Cellars but dangerous in Abyss of Demons due to lava. In addition, the Ninja has to go in pretty deep in order to get lots of hits, so it can be dangerous if you are not 8/8 or with a knight. The ninja is very useful against dungeon bosses, such Oryx the Mad God 2, Stheno the Snake Queen and other bosses who do not move a lot. Note: It is possible to consistently have the Speedy effect with a good enough MP Heal pet.
Is a good class if you have a good dagger: with the special ability you can distract enemies while you kill them. This strategy is very useful when fighting with a lot of enemies at the same time (i.e, Cyclops God). You can use this ability for pass through god like Medusa or Beholder much more easier (but go careful because there can be more gods after this!) and go to the quest very fast. If you use the trickster's ability for the teleporting more than the decoy, then keeping a T0 prism (starter prism) with you is a good strategy.