1) Before creating your character you must post a sample RP and wait for it to be graded. This will determine how powerful your character can be. grades will be as follows:
D: allows a player to make Humans, both combatant or non-combatant
C: Allows a player to make characters that are basic Soul reapers and Hollows
B: Allows a player to make characters up to Lieutenant rank or Hollows up to Adjuchas level
A: Allows a player to make character up to , Arrancar at the Números or Fracción, or menos at the Vasto Lorde level
S: Allows a player to create a character up the the Captain Rank as well as Arrancar at any level (Including Espada and the Privaron Espada), or Vizards.
2) When posting your sample try not to control NPC characters. This shows that your RP skills are low in situations when there are not many people around and controlling NPC characters will lower your grade.
3) Remember to use proper spelling and grammar when posting. Poor spelling and grammar will result in a slightly lower grade.
4) Para RPing will lower your grade more then anything. Give sufficient detail but don't go overboard. Giving to much information can confuse people who are trying to read you post, and its just plain annoying.
5) RP samples that are not combat type RP samples will get the best grades as it shows that you can be creative when your not fighting. This leads me to believe that you will post well in fights as well, making me want to give you a better grade.