Until 105 you can follow the quest lines and make your exalted quests. Those provide you free gear.
After that it really depends on what you want to do. There's bloody gear for PVE and dark gear for PVP (R99 and R110), so you would basically need to upgrade everything (shirt, circlet, armor, weapon, brooch jewels, artifacts, agathions, RB jewels, etc). That you can only get from players or from L2 Store, hence the credit card comment. Because you need adena to buy gear to make more adena. And just farming on open field with exalted gear at 105, it's not easy to make adena.