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 traffic sign colours.
Staircases and escalators
Probably this is what you might fear the most. But don’t worry too much. An exposure would require a staircase being as steep as ladder - and that 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 give you the needed protection. The back of your kilt is more problematic. Holding your hands discretely 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 recognize what is under your kilt.
And should somebody have a look to black briefs or the like, it is not that 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 (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 often 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 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 time lap. Except for cropping them and afterwards incorporating the red warning and decency spot, they haven't been manipulated in any way! They are as is.
Conclusion: Just not the kind of day, you should go commando.
Sitting and sitting down
One of the advantages wearing trousers is that you can sit and sit down without taking any care. With a skirted garment it is not that simple.
Women seem per instinct to know how to sit in a skirt – even if they are seldom wearing one. With a kilt it is the same, but we men don’t have the instinct feeling of how to do.
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 streth out your legs in front of you...
or streth them to the left or right.
Crossed ankles are fine.
Crossed legs, i.e. tighs, call for some aattention, especially when changing position. 
But 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 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 had been possible with a smart phone on a selfie stick. Or just the phone. The problem is real and to 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 women in skirts have been thought of, it is to expect that men in kilts are protected by the same law.
Now, should some pervert nevertheless be able to take a picture of you from below, the picture should most likely be bad due to lack of light. And, most important, 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; make a plan for when and 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 neighbour city. In the streets, in museums, at restaurants, in shops, and in public transportation.
Regarding duration, make it hours, not just a few minutes from leaving your car till being 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 shall give you a second glance. Not because they do not like your kilt, but because it is different. After a few hours you probably should not want to ever 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.
