Go to the Mist Generator and walk around the outside wall until you are attacked. Fight to get up to 204 experience points. When low on HP and MP, go to Biron or Hunters Spring and then repeat the process. Note: You will not get as much gold at the Mist Generator. If gold is needed, go outside Biron towards East Voz.
Go out where there are mist and monsters. Fighting these monsters raises up your characters' levels, but patience is the key.