So you've finished downloading rose and are playing for your first time, or maybe you just wanted to create another character either way this guide is for those who want to level up quickly.
Level 1-20 (3-4 hours)
You start off at newbie island, the first thing you should do is talk to the fairy go through EVERY saying possible (expect the very last one) she will give you experence with every saying that you go through. This is an easy level and a half, or maybe more. After you do that, take all the quests she gives you and complete them, it shouldn't take more than 30 minutes to do all this (During this time you should put your stat points on str no matter what class you want to become later on. You can reset them later.)
Now talk to the fairy again and transfer to adventure plane. First thing you would do is talk to every npc (especially gray and sanon) get all the quests you can. Kill stuff until you are about level 4 if you weren't before you left the island. Now make sure that you have the quest from Sanon about the item prices. Make your way North and kill stuff as you go. Keep going North until you enter the valley of luxem tower, once you are there you are probably to low of a level to kill anything so just keep going North until you reach Zant. Once in Zant go North then East in town and talk to a guy named Yuresis he will give you a load of experience for bringing him the prices, then tell him you want to do him a favor and he will give you another price quest. Go back to Sanon in adventure plane and give him the price list (killing stuff on the way there and the way back). Keep running between Sanon and Yuresis until you are level 10 then go get a job change and you might want to reset your stats by talk to the guy next to Warren. Now continue going between Sanon and Yuresis until you are level 20.
Level 20-40 (7-9 hours)
There is really no easy way to go about this, but I can give you some suggestions to make this whole process quicker. First off in adventure plane the fisherman Maaed gives you a quest about mushrooms or somehing this is the luna quest do this quest as much as possible as you go through the game, it will give you loads of experience, zuly, and items. (if you get stuck at one part, forget about the quest for a while and just go level up). Now that you are at level 20 you are going to want to train just outside of Zant. Kill Woopys until they are not longer yellow. At this point you want to move onto Hill of Wind here you want to kill either beetle bugs or red formics (don't waste your time on the guards they always take a bit longer to kill and give almost no experence compared to the attack monsters) once these become somewhat easy for you, you can move onto lekis start of with the regular ones until they are no longer a challenge (of course if these are easy for you try the harder lekis). Now move onto Elveroon. (Far east in Hill of Wind) If you decide to train here kill turtles like crazy (should be very easy for the hawker class because the turtle's attack is very slow). Once turtles become somewhat easier you can move onto aquas. If you decide to move onto aquas don't waste your time in elveroon the aqua spawn is way too crowded and you are kill stolen constantly. Move onto anima (northwest of elveroon), the aquas are located by the northeast spawn point (and you have a chance to attack the aqua king). When you reach level 30 be sure to goto Junon and join a union (I joined the righteous knigths and the quests for this union are to kill moldys, grunters, and porkies. Whatever union you join you are going to want to do all the quests that are easy for you from them, you want as many union points as possilbe, 160 union points = car) Continue on aquas until you are close to level 40 even though they become very easy you can kill them very quick and the aqua king still gives decent experence.
Level 40-60 (12+ hours)
Whatever union you joined if you do not have 160 union points continue on those quests until the monsters that they have you kill become too easy. The next place you want to go around level 44 is the forest of wisdom, go up the road until you reach the guardian tree spawn (northwest). Train on grunters and attack the guardian trees/grunters when they spawn. This will give you lots of experence very quickly. Also if you have an area attack (ie sprial kick, or wind storm) you can use it on the scarbes that spawn around the guardian tree, this yields a lot experence. When you can solo old trees you can move onto clowns and the area just outside the beach of genzi. This is where a lot of grunter kings will spawn which also give you a lot of experience. Kill everything in sight until one spawn then attack it until it is dead. After you are about level 54 (maybe sooner) you can move onto Elder Doongas at the beach of genzi (or you can go to the goblin cave and level on b1). Either one is good for leveling but the goblins in the cave tend to drop refine materials. Continue training in one of these areas until you are level 60. (as you go through this process make sure you are still doing the luna quest continues from the quest you get from Maaed). Of course when you get to level 50 you should go do the drivers license quest (see another guide).
Well there you go, that's what I would suggest to level the fastest (while still getting a car for free).