Trying to convert a male outfit onto a female mesh.

Hello, 

I am relatively new here to this community and I have been experimenting with Blender. What I am trying to do is convert an outfit for males to fit that of a female model. I've experimented with how to do this, but keep falling short because the neck in particular and shoulders are much too broad. 

I have tried to search for numerous tutorials on this, but it seems that no one has really created a step by step on how to do this. 

If anyone is able to provide any insight on how exactly to do this that would be great. 

Thanks!