-Birth village
Here is where u get to know the general NPC's and for everyone except archers, get some starter skills (more on that later). Now, you can go there or just say "forget this, I want to go and play now" if u already know the info.
-Lv. 1-14
Note that you can only go in through these levels once only!!!
You should have 100 silver, a lucky Item, a coat, and three healing pots (potions). Now you should use the money you have to buy more pots. Equip the items you have then go hunting just out of twin city. Another way to go through this point (because u can't lose items while your in these lvls.) is to use the silver u have and go to a really tough place like bird island, pick up money there and ask someone to power level you, then go back.
-Lv. 15-35
Now this is where things really pick up speed. At this point u should have some armor that only your class can wear and get promoted for your lv 15 job. You should move from twin city plain to the maple forest (the portal is on the lower right corner of the twin city area). Here u can ask someone to continue power leveling you or you can train yourself. Note that you should repair your equipment about every 2 hrs of gaming time. 
-Lv 36-60
Now you're starting to get powerful. You should move to one of the other cities (there are 5 total), and continue training there. By now you should have at least one friend to help train you. Go back to twin city at lv. 40 to get your second promotion. By now you should know what mets is (FYI they're meteors!!!). And use them. in the market.
-Lv.61-100
You should have an emerald to get your lv. 70 promotions at twin city. You can go keep training at the city you chose or go to another one and train there.
-lv. 101-130
At this point you can get your level 100 and 110 promotion (you need a meteor and a moon box and get a rainbow gem and a Dragonball [no not from dbz]). Now you can get reborn (you get a bottle of clean water and 7 different types of normal gems.)