What are the best wishes?

[Puppet Pal Clem]

how should i use my dragon balls?

[Phrasmotic]

Depends on what you want really. Don't wish for TP Medals or Zeni since you can farm it quicker from PQs. Don't wish to level up since levelling up is already really quick. Wish for ultimate attacks if you don;t have them yet, but they aren't absolute must haves so you can leave that until last. Wish to dress up if you want the silver and gold armour as it's the only way to get it.

Personally I think the most useful thing to wish for is to change your attribute points.

[Black_Knight]

Characters and Skills. Anything else is pretty useless unless you want to change your appearance and attributes, but that's only if you're unsatisfied with your character

[Ebon Wolf]

Characters and skills. If you mess up your build, a new life is good too.

[ImPulse01]

Characters first four times. After that skills and stuff. if they release a level 99 patch then you should use that