To do this select a class with an active or passive skill you want, such as the fighter's Quick HP Regen, mage's Attack Spell, or a priest's Healing. Level up, select skill, then set to active or passive slot. Then, change class. ALL set skills will now remain until you remove them.
Items Remain with New FileAdded 15 Dec 2009, ID #3375
To do this glitch put ALL your equipment and money in your house then save and quit the game. Delete your file and start a new file and when you check your house ALL your items will be there from the deleted file.