As a new user of MYOB, it'd be great to have a helper interface that notes fields that are not required to be filled out marked in some way. For example they could be outline in a different colour or have an icon next to them. This interface could then be turned off for advanced users. I'd expect having the default as not highlighting the optional fields.
Also in this helper interface, each field could have a tooltip which briefly explains what the field is for and a link for more info which opens in a new window.