How do we, average citizens, best respond to terrorism?

Pretty much as you said.

We can’t ignore it or pretend that it hasn’t happened. But we also can’t be consumed by it or terrified – however much the perpetrators intend that – to shut out the world or assume that “everyone who looks like them” has that in mind for us. Or change our beliefs and actions (outwardly, anyway) to pretend to conform with the ridiculous demands to “submit to Allah.” If Allah needs my compliance to make its will felt, then Allah can’t be much of a God, can he?

I work among Muslims (and Hindus, too – as well as the majority Christians and the healthy minority of Jews one would expect to find in an American office setting), and I have also worked and traveled through Muslim and Hindu countries. The people I have met are among the quietest and most peaceful that I’ve ever met. Apparently, they’re not very strict Muslims, Hindus, Christians and Jews – and thank God for that.

That’s not to say that “there is nothing at all wrong with Islam” – or Christianity, Judaism or Hinduism, either. (Maybe a fundamentalist Jainist would not want to kill those who disagree with him, but I’m not looking for one to test that theory, either.)

Mostly what I’m doing is continuing to shun and resist fundamentalists of any religion, or those who assume that violence is the best answer to insanity. Awareness, protection and defense, sure. But not “kill them all” violence.

@CWOTUS Thank you. I appreciate the careful thought you put into your answer. It mixes well with my OP. I agree with the idea we must resist and not be consumed by the terror.

Yep, the same, all we can do.
I agree with @CWOTUS as well, reject all fundamentalist beliefs and just go about my day, doing what I can. Somewhere in the hills of Northern CA. right now, the sun is shining, it’s a stellar spring day and life goes on. I gave up being codependent on the world years ago and accept that sad and bad things happen, always have, always will, such is the nature of life.

Live one’s life as though it isn’t happening to the best of one’s ability as they have stated very clearly that disrupting our way of life is their aim.

This can be a challenge as some US agencies are effectively complicit with the bringers of terror. I’m looking at YOU CIA. YOU FUCKING BASTARDS. YOU KNUCLEDRAGGERS INTIMIDATE, YOU THROW YOUR PETTY LIVES IN MY FACE AND DELAY ME. YOU SPOKE TO MY FATHER AS IF HE WAS A CHILD.

I WANT MY GODDAMN LIGHTER BACK YOU GORILLAS. IT WAS A PROMOTION PRESENT. YOU RETRIGGERED MY ANXIETY DISORDER AFTER MONTHS OF IMPROVEMENT.

BURN IN HELL EVERY LAST ONE OF YOU.

It would depend how directly affected you are. If someone close to you was killed or maimed your reaction will be different to watching the news on television. If the terror continues to kill and injure those around you your reaction will be even stronger. Terrorism itself is often a reaction to terror. We feel forced to react to protect ourselves from inhuman enemies and so we become inhuman. For now, I am not changed by it, and I go about my life as before.

There are a number of things we can/should do. I mentioned here a while ago that my daughters were travelling around Europe last year. They returned home just before the Paris attacks. Before they went, I was nervous about them travelling. I’d actually been in Europe the month before they were there but didn’t feel nervous for myself. My children are a different issue. My heart wanted to tell them to stay home and be safe, but my head told me they have to live their lives. As do we all. We have to keep doing the things we love and visiting the places we want to visit. If we don’t, those who encourage, plan and execute these acts of terrorism, win. They achieve their goals.

Our second response is to be more vigilant and observant and alert. More acts of terrorism are certain rather than possible. So we need to notice when we see bags left unattended. Observe how people are behaving around us. Listen to our instincts. Take note of security warnings. Be patient when we experience increased security measures.

I think we also need to resist the temptation to begin to blame and judge any particular group in society. Most Muslim people are not terrorists and do not condone terrorism. Just as we cannot allow terrorism to change how we live our lives, we can’t allow these acts to make us hate.

Keep calm and carry on.

Everything already said, but especially the second paragraph in @Earthbound_Misfit‘s post.
Was going to say exactly that until I saw, so true.

The first thing to do is realize that your chances of being personally involved in a terrorist episode are about as likely as winning the lottery. The same holds true for you even knowing someone involved.

We must be alert, but we must not live in fear. We can balance out these (sometimes not so) random acts of violence with random acts of kindness. Refuse to live in fear, and live instead from a viewpoint of compassion.

Pray not only for the afflicted but that NO More harmful acts such as these occur.
Pray for the offenders to come to peaceful ways of solving their problems.
Pray for Peace, compassion, and understanding.