What's the best way to stop the panic attacks from beginning?

The best thing you can do is to stop your thoughts. Do this by pausing whatever you are doing. Go to a space where you feel safe. If you cannot, create a mental space. Sit, and just breathe. Focus on your breath. When a thought comes into your mind, gently tell it to go away and mind its own business. If you aren't thinking, then your mind has no fuel with which to attack you with. Breathe. Just breathe.

Take a step back and breathe. If your mind panics, your body will follow - but this also works the other way around. Focused breathing will give you something to occupy your mind with other than stressful thoughts, and it will ground you in your body and the now so you won't get carried away. None of this means you should ignore what you feel: acknowledge the feelings of panic, but don't focus to hard on them - just ride them out. Remind yourself that you control the feelings and that they do not control you, and breathe.

Try to realize what triggers your panic attacks. A lot of times there are no triggers, but if you can pin point what causes your panic attacks you can prevent them from happening.

I usually, when I have panic or a friend is having a panic attack, is close my/their eyes and focus on a sound. If you focus hard enough then your nerves will calm down and then you'll know for next time.

Deep Breathing (in through your nose, out through your mouth), guided imagery(i'm on a beach with clear water and white sand and bright sunshine), and stretching help distract me from anxious thoughts

Knowing your triggers is, from my experience, one of the best ways to prevent panic attacks. Also, knowing what the start of a panic attack feels like (racing heart, sweats, dry mouth, shaking etc) can help you find someplace safe and quiet to ride out the panic attack.

I have them all the time, it comes back to you to be strong and calm enough to prevent them. If it's not working consult an expert. Be strong

Deal with your fears and problems through self -development, Understand that your fears and thoughts don't exist around you, they just exist in your brain.

I saw a cool trick on Reddit a while back. When you feel anxiety coming on, blowing air onto your thumb can calm you down. It works, somehow.

Know what makes you have panic attacks and try your best to avoid those situations. Do whatever makes you calm.