If you really want to approach a female voice without any technical gadgets, I can give you a few tips, because I am an intersex woman (born with mixed chromosomes) who suffered from a voice break due to testosterone in my youth and have been trying to get rid of the masculine voice that misrepresents my sex for years.
The most important technique used is not just to try to raise the frequency of your voice (that usually doesn't help much and can be a strain to your voice), but to try to lift up your adams apple (thyroid cartilage) while speaking/singing. This is very tough to learn, but if you succeed, it reduces the resonance of your air cavities, and sounds more female.
For me, this technique is still problematic and not sufficient, so I just underwent a surgery to shorten my vocal chords two weeks ago. It will take 3 months until I might be able to speak loud enough again - that's certainly not something you'd consider...