My suggestions (LONG)

SUGGESTION A (Leveling)

I suggest that you have basic "jobs" that you can choose from.
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Warrior
Mage
Bowman
Pirate
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When you reach a certain level, you can unlock different jobs, such as.
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Thief
Tailsman
Knight/Soldier
Etc
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There would be a maximum level of 255.
I suggest you make areas to these levels. Also to have islands based on the levels listed.
Level 1-10
Level 10-30
Level 30-50
Level 50-70
Level 70-100
Level 100-150
Level 150+

Also for the leveling system, there would be a LOT of weak enemies on the island where you could kill them easily and get good exp. The leveling system would take a path like this.
Level 1, exp 7
Level 2, exp 14
Level 3, exp 24
Level 4, exp 31
Level 5, exp 56
Level 6, exp 78 etc

SUGGESTION B (Money)

For this server to run for a while, you need some dough. I don't got much on me and when I have a yard sale, I'll get a lot off of the stuff, and I might donate about 100$ or less. Anyways some ways to keep it running :

(1) Have people donate to you
(2) Have people pay you to advertise their stuff here
(3) Make cool items that you got to buy

Now for 1, you could have a campaign.
For 2, You know..
For three, have Items that give you stats like all stats +10, HP +100, for about $3.00, etc..

For the classes im trying to go a little bit more original seeing as those classes are seen in every single mmo these days, but i completely see where your coming from and i like the idea of later classes.

the leveling is a good idea, i was thinking of more of a 100 level cap, but 255 may not be a bad idea.

pirata currently runs on a pretty decent vps but yeah money will always be an issue, but i will not be opening a shop until vampyr and pirata are both stable enough to where i will not have to have account wipes/etc.

i really don't like the idea of the leveling by killing, this means there will be much grind in the game and players don't like that (grind= repeating a action over and over again to get a certain level, statement, achievement)

what i suggest (but thats taking much time)
- make lots of quests that give players exp, let them do every day something exiting on PIRATA
- make a main story line, a group of quests following each other
- make instances, raids to give players lots of exp

meaby this is the actual idea, and in that case: forgive me,

i'm making a MMO to, with the RPGXP engine, meaby we can work together on our games

I hav RMVX but im not that good