
All your life, you have been wearing trousers. You just wear them without much consideration, if any. But with an "open" garment like a kilt, it is different, quite different. The way it looks, and the way it feels. When you start wearing it out and about, you might therefore feel kind of vulnerable and afraid of doing something wrong. And yes, there are a few things which need your attention. And some others you might fear without reason.
What if I do something wrong?
Here we talk casual wear, not national dress. Accordingly, you can and should forget about most and often rigid rules, apart from a general proper appearance.
And honestly, how likely is it that you shall ever meet an “expert”? And, should you, how likely do you think it is that this person should be impolite enough to blame you?
Dangers
No doubt, your biggest concern is the risk of exposing yourself. Below, different situations are described, and the degree of danger is illustrated by colours from traffic signs.
Staircases and escalators
Probably, this is what you might fear the most. But don’t worry too much. An exposure would require a staircase as steep as a ladder, and someone was climbing up directly under you, or a nasty person with a selfie stick. Also, in most situations, there shall probably be a deep shadow under your kilt.

Not even Photoshop should be of any help here.
Windy days
It does take more than a little breeze to really lift your kilt, but wind should not be totally neglected. On your front, the sporran will, in practically all situations, provide the needed protection. The back of your kilt is more problematic. Holding your hands discreetly as far down your sides as possible will prevent it from being around your ears, but a strong wind might nevertheless make it go up. In most cases, however, it is just a question of a second or two before it is safe down again, hardly enough for anybody to really recognise what is under your kilt.
And should somebody have a look at black briefs or the like, it is not a big deal after all.
If not wearing any? Well, humiliating and embarrassing, of course, but in liberal Western European countries, and if you obviously are not deliberately exposing yourself, hardly anyone should be too much shocked. After all, it is a kilt, isn't it? Point.
A shoulder bag (a photo bag, computer bag or messenger bag) can be helpful, when really windy. Make the strap as long as possible and have the bag cover the back of your kilt as far as it goes.
By the way, how often have you seen what woman are wearing under their, sometimes, very short skirts?
Don’t be
too concerned about wind,
but be aware that, on some days, unpredictable wind gusts
can be quite annoying.

Utilikilt at the Mediterranean.

Seconds after, it got a bit windy with some movement in the kilt.

Then a sudden wind gust...

...and seconds after, rather calm again.
Above, four pictures are taken with a few seconds between them with a time-lapse. Except for cropping them and afterwards incorporating the red warning and decency spot, they haven't been manipulated in any way! They are as they are.
Conclusion: Just not the kind of day, you should go commando.
Sitting and sitting down
One of the advantages of wearing trousers is that you can sit without taking much care. With a skirted garment, it is not that simple.
Women seem by instinct to know how to sit in a skirt, even if they seldom wear one. With a kilt, it is the same, but we men don’t have the instinctive feeling of how to do it.
When you sit down, smooth the pleats of the kilt beneath you to prevent it from twinkling, but foremost to secure that you are sitting on the fabric, not directly on the chair.

When sitting, keep your legs, especially your knees, together, like here.

You may stretch out your legs in front of you...

... or stretch them to the left or right.

Crossed ankles are fine.

Crossed legs, i.e. thighs, call for some attention, especially when changing position.

But it can be managed.

More luck than wisdom. You should never spread your legs. If you do, make sure the front of your kilt is down between your legs.

Men are sitting this way. But in a kilt, it doesn't work.
KEEP YOUR LEGS TOGETHER!
Never forget that people might have a focus on your legs (in restaurants, on benches in parks, etc.). Because of your kilt.
Picking up something or leaning forward
ATTENTION!
Picking up something and leaning forward are by far the most dangerous situations when wearing a kilt.

You have dropped something, which you'll pick up, or you are going to tie your shoelaces, OR you are about to take a product from the lowest shelf in the supermarket, ALWAYS bend your knees. Never ever just bend over!

You have seen something interesting down under you, like when standing on a bridge, or you are looking down on the street from a tower. Whatever it is, never lean forward when in a kilt.
Keep in mind, red spots are only available and helpful on your computer. In the open and in the city, you are on your own!
People with selfie sticks
Earlier, kilted soldiers could be checked for forbidden underwear by means of a mirror on a stick. Today, it has been possible with a smartphone on a selfie stick. Or just the phone. The problem is real and must be taken seriously. "Upskirting", as it is called, has since 2010 been illegal in Scotland, and so it is or is about to be in other countries as well. Even if the law is to protect women wearing skirts, it is expected that it also protects men in kilts
Now, should some pervert nevertheless be able to take a picture of you from below, the picture should most likely be bad due to a lack of light. And, most importantly, your face could not possibly be in the same picture.

.
Self-confidence matters
Self-confidence is extremely important. If you don't have it, build it up; have a plan for when, where and for how long to be out in public the first time. And stick to it.
In public could be defined as being in the open, on a not too deserted place, or in a neighbouring city. In the streets, in museums, at restaurants, in shops, and on public transportation.
Regarding duration, make it hours, not just a few minutes from leaving your car before you're back. And be prepared to answer, if being asked questions or when meeting someone who knows you.
You must be man enough
Soon you’ll get accustomed to being kilted. Some people will give you a second glance. Not because they do not like your kilt, but because it is different. After a few hours, you will probably never want to wear pants again! Here, you must be man enough, however. You cannot wear a kilt all the time,
but…
Be aware that a never-ending addiction might start the moment you try on a kilt.