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... :)

This is good youtube channel about danish pronounciation: http://www.youtube.com/channel/UCELY640l4PvwswWPTfMQ5YA He explaines everything in Danish, but he also draws tables and pictures, you can understand everything even without speaking the language. (that's what I do :)) And his playlist with videos about vowels: http://www.youtube.com/watch?v=dr7hU_iP0dw&list=PLk6g9tySafapZslHn-nXJ9nMhRF9gwtRA