Well I will tell you, that they are all very different. Maybe someone here can point to some ressources, where the sounds are recorded.
Else words like
Om (around), som (as), dom (conviction)
Bus (bus), lus (lice), snus (snuff)
Øre (ear), høre (hear), skøre (crazy)
Are good suggestions for hearing the pronunciations.
Else you are welcome to PM me for my skype. I will gladly use half an hour or so of my life, to help you with your o-u-ø issue :)) Happy that you are learning the beautiful danish language btw... :)