One of the best ways men can use their male privilege to create a safer space for women is by staying on high alert in public spaces. It's easy to miss, but there are sadly many cases in which women are leered at on public transportation and followed and harassed by strange men. Approaching a woman and pretending to know her, while awkward, can in many cases diffuse a situation with a harasser - since men tend to fear other men more.
However, given the fact that many cases of harassment are less visible to onlookers, women are often faced with the minefield of trying to judge who will be a safe ally in these moments. Other women tend to understand the struggle, but can also get targeted themselves, while men are the perpetrators in the first place - making it scarier to reach out to a strange one. Luckily, there are men who want to help, and not all horror stories end in tragedy.