(This is outdated) however still relevant whomever wishes to update or provide a more detailed guide please do so. Linked here : )

The Mage class is probably the most common class of all in the game. This is the only class with the ability to hit all of the enemies at once in battle. With the quick and cheap spells you have early on, this is a very powerful choice for starting players. Later in the game however, the EC level of a mage rises more slowly and the level rises faster. Which means you'll be doing a lot less damage up in higher levels of the game. But being that your spells can be of any element and can hit both rows of enemies this is still a very powerful class. The main problem with this class, is that to be effective in later level battles you need a lot of MP, and to do that, it means you'll be lacking in constitution and HP.

Getting Started:
Ok, now if you read the basic info section before diving into this, you'd have learned not to go straight into the diviner apprentice. Spending your first 10 levels as a warrior apprentice is a much better idea. As a diviner pre-mage, you have no skills to level as an apprentice. So having the warrior skills and ability wear armor and use weapons will help you quickly get to level 10. Then once you hit level 10, drop the warrior apprentice, then pick up diviner and go get your mage class. Now you have some spells to use.

Stat Distribution:
The most important thing for the mage is of course MP. And the more Intelligence you have, the higher your chances are of getting more MP each level. Intelligence also increases MP regeneration, which will allow you more pets. Enhancement and healing pets will be your life blood, so it's good to have high intelligence for that reason alone. So as for main stat distrubution I recommend grabbing just a little bit of con between starting and level 10. I'd stop at around 25-30 constitution, that'll give you enough to have a decent HP gain on levels, but won't take away too much from your more important stats. Those more important stats are intelligence and dexterity. Pumping intelligence up quickly is key, so if you pump 1 int and 2 con between level 1 and level 10, you should be doing good. Then afterwards a nice healthy growth of int and dex would be 2 to 1. So 2 int and 1 dex per level.

Now that you're at level 10, you've finally become a mage.
The most important thing with being a mage, is in battle, you should never do anything but use spells. Your spell damage is based on your elemental control level. And the only way to gain levels in elemental control is to use your spells. The higher the level of spell you use, the more experience you'll get. To do this you'll need a lot of mp, but you have the prayer skill, so that's not important. But then you have to worry about your HP, this is where a good healing pet comes into play. Grab yourself a light owl. Light Owls are low level, between 10 and 12, so you can use them immediately, and you can also immediately teach them recovery at the light temple. The recovery pet skill will be able to heal you and the owl and anyone else you may be partying with IN BATTLE, not outside. This will lower your need for pots to just about 0.

Pets:
Pets, pets, pets. Pets are very important to a mage. Since you have the ability to throw around spells like fireball and flame hail, you'll cut through mobs faster. Which means the lowered experience you get from using multiple pets isn't so bad. So go ahead and collect yourself a group of pets. You'll want at least 3. One pet for combat/healing, one pet for magic enhancement, and one for armor. Here's a few choices you have to go through. I recommend you choose and obtain at least one of each of these, and then train them up with you.

Healing/Combat - Light owl, light sheep, gem crawler, rice bunny, light pegasus, light cloud, light beetle, and light hedgehog.

Magic Enhancement- Black sheep, Big Bad Wolf, Dark Rat, and Dark Unicorn.

Armor Enhancement-

Pure Defense- Wood Crab, Pie Aibo, Wood Poli, Wood Hog

Defense and Dodge- Mud Slime, Mutt, and Earth Poli

Where should I go to beat things up now?
Since mages can hit cast row and even group damage spells, solo playing with them is mostly a walk in the park. You'll be able to drain in dungeons more easily than the single hit classes. That means quicker and easier experience, that translates into quick leveling. So here, I'm not posting a lot of diverse routes and mainly sticking with the slime cave. The reason being is that you will level the fastest here no matter what in those areas.

Training:

10-15- Here, with the mage, is where you'll have to take it a bit easy. You'll need to quickly get your EC levels up to at least 12 so you can learn your row damage spells, avalanche and fireball. So going straight into the slime caves or out into major combat areas isn't very smart. Since you'll be working with rather weak single target spells, you'll want to stay around your villiage and fight the weaker monsters. You might even want to fight the little level 1-3 monsters just outside the small villiages to get your EC up quickly. The beauty of the elemental control, is that it levels up just by using magic, it doesn't matter what you're casting it against.

15-20- By this point you should have your row damaging spells and be working your way up the EC charts. Now you'll want to head into the slime caves. The slime caves will be your home for leveling for quite a while, so get comfortable in there. Once you start getting too little experience from combatting the puppets and slimes, move up to level 2 in the slime caves. Here you'll be up against more worthy apponent but the experience will be much higher, and as long as you've got your pets with you, you shouldn't have any problem.

20-25- Here you'll still be in level 2 of the slime caves. As the experience starts to come more slowly, you'll want to move west and start fighting the light and dark slimes. Watch out for these, they can be a handful. Those dark slimes love to cast spells. Dimension distortion and poison aren't a whole lot of fun when they're pointed at you. Your healing and armor pets will be getting a lot of use here. But what you take in damage, you'll more than make up for in experience.

25-30- Here's where you finish up soloing against those annoying light and dark slimes and move on to the bigger fish. Slime cave level 3. If you're not comfortable fighting the monsters in here yet, you should still be getting enough exp. from those light and darkies to keep you occupied for a couple of levels, then you can move on up.

30-35- Here you can finally move out of the slime caves and put some diversity in your life. Now you should have well over level 36 EC and a thirst for blood. Having spells such as inferno and wrath of lands in your fingertips, you can pretty much go wherever you want to. Goldburg lake might be some good game, or maybe crystal mountain, sleepy lake. Anywhere you can find monsters at or around your level.

35-40- Same applies here, the main strategy is to keep the mobs at or around your level. For this you'll want to head to places like moonglow, the tanrana maze, the dark caves, etc.

40 and beyond- For this, much like all classes, you're at a loss of experience until updates. You can continue fighting the level 40 mobs for for a few levels. But like other classes, if you want to power level after this point, you're going to want to find an acolyte of darkness that has the dark ritual spell to help you out

Leveling (Mages)
RESPONSE BY:

Colby Lee Cross
           I just want to say that you do not need to go to Candy Mountain to get 500-1k exp as said in the previous lvling guide.  All you need to do is go 2 slime maze 1 2 or 3(depending on your lvl) without a pet. I suggest that when you get fireball and avalanche..hunt around SL1 till you get to about lvl 18-20 and Flame Hail(and Blizzard)then you can start going to SL2.  Then when you feel brave enough you can go challenge the Wood Eagles and Water Slimes in SL3.  I'm lvl 24 and at Slime Maze 2 with no pet...I get 1k-1.5k exp from fighting the white and black slimes.  So..I really don't think I need to risk it and go to Candy Mountain