I just wanted some advice off someone whos good at texture maps. I may have asked this question before, so i apologize in advance if i have. When opening a UV map is it ok to just change the width or the length so your uv map isn't squished. Cos whenever i put little bits of detail onto tex maps i normally have to resize them because when rendered the details come out stretched width ways or length ways.

Yes, you can alter the dimensions of any UV map to suit your needs. Ideally, a texture should not stretch or squash when it's mapped onto an object but there are times when it's unavoidable, such as when the tex goes around several curved areas.