Babybear, in most of the world it works this way:
IFR:
Odd thousands on easterly tracks
Even thousands on westerly tracks
VFR:
Odd thousands plus 500 on easterly tracks
Even thousands plus 500 on westerly tracks
I know there are variations in some countries, e.g. New Zealand uses northerly/southerly rather than easterly/westerly.
In Australia and NZ standard altitudes or flight levels are mandatory for all aircraft above a specified altitude or height AGL.