Like a Dragon: Infinite Wealth

It might seem like obvious advice, but the best path to getting this is to commit to a single job and keep grinding away until you've reached rank 30. It's then a case of heading over to the nearest branch of Alo-Happy Tours (check your map – there are loads of them) to change jobs and start the grind all over again. Look out for magazines, too – these are growth items you can use to boost job's EXP. If you keep all of your party's jobs the same, however, each character's job rank count towards this, so it's actually surprisingly straightforward.