i wanna purchase a tutorial that may describe specially making uv’s and rendering maps in external 3d application…plez suggest me a good tutorial 
hello,
I’m not sure if theres such a specific training DVD man, but you can check out the Gnomon workshop series.
Btw, what 3d app are you using man?
i’m using max and maya apart form zbrush:):)
heya,
im a max user. have you tried using the max user reference on uv unwrap?
it shows you pretty much everything you need to know about laying out good uvs for your model.
btw, is there a specific problem you have with your uv layout?