I stumbled upon a way that works for me.
I will always have high anxiety, but panic attacks for me are usually triggered by anxiety feeding upon itself. I feel anxiety, worry about having a panic attack which makes the anxiety worse, ad leads to a panic attack.
For a good year I did mindfulness meditation. In that time I didn't feel like the meditation was doing much to lower anxiety. I think I kind of had mindfulness a bit backwards. I used to think mindfulness meditation was about clearing the mind in order not to concentrate on anxious feelings. Now I sort of think it is more about analysing my own thoughts and viewing them objectively.
I tried meditating in the middle of a panic attack which sometimes kind of works if I am alone, but not really in public. I remember one job interview where I meditated for 20 mins before in the car, felt calm, then had a panic attack in the middle of the interview. I ended up stopping doing it thinking it was a waste of time.
A while later I read a paragraph on reddit somewhere that sort of changed everything for me. It was something along the lines of don't try and calm down during a panic attack, or try and distract yourself, just concentrate on the feeling of anxiety and wait for it to pass.
I started doing this and haven't had a panic attack since. Whenever I feel like a panic attack happens I really concentrate on it as much as I can. Sometimes I try and panic more, almost to try and bring on a panic attack, but it never comes.
For me I think this was important because it is a mistake to try and calm down during a panic attack. My brain says to itself holy shit there is a problem here and we need to worry about it to try and fix it, and it just gets worse. By facing the panic head on it removes the feeling of danger of panic, and the panic attack never happens.
I think the mindfulness meditation ended up helping a lot, as it sort of trained my brain to watch what I was feeling, which allowed me to sit with the panic. I think I will always have high anxiety, but hopefully no more panic attacks.
Sorry for the wall of text, but it is kind of hard to explain. Hopefully it makes some sense.