I think that there is some things we should tighten up.
For example how many that can have eaten a devil fruit, how rare they should be and which devil fruits that should be unobtainable.
Or else everyone goes around with insane powers.
Also, a technique field could be useful, so people don't just make up over-the-top techniques from the very beginning; let them train in the topics to get stronger, as in every other rp.
A level up system should also be considered, since everyone just ends up being monsters from the start if there isn't one, and that will be kind of stupid to be honest.
There should be some kind of restriction, so people have to work off their butt in the rp's, if they want to become stronger.
- Of course without making it impossible for them to level up into stronger beings.