I’ve been involved with martial arts and self-defense since 2004 and teaching self-defense classes since 2009.
There are a few things I recommend a women carry with her at all times in a place she can easily get a hold of….Pepper spray (18% or higher), tactical flash light, personal alarm, kubaton, and a sturdy metal pen. Now if your country, state or city allows you to carry a gun, that would be nice too. All of these items will be taken from you if you want to board an airplane or go into a government building except the metal pen. The pen maybe X-Rayed but won’t be taken from you.
Now when I say you should carry these things I mean you should also be trained and ready to use each of these items correctly. Here’s a video I made to show how to use these items
Original question and answer link How Can A Woman Defend Herself From Attackers?