Unless someone has a very deep voice like some stereotypical alcoholic sailor, there is an easy way to make it sound more female .
Just tighten up your throat just a bit as if you were about to gargle and speak .
Practice this a few times and you will be amazed how female you sound......without resorting to an awful falsetto.
BTW....
Some females do indeed have a rather deep voice.
Also in most situations when shopping, you only have to say a very few words most of the time anyway .
So, do not be afraid to speak when you have to.
