There is a trap that libertarians often fall into. It is a trap set by someone challenging the libertarian philosophy, whether it is intentional or not. Sometime the challenger is simply asking, with no ill intentions, and is looking for a serious answer.
The trap is when libertarians feel the need to have all of the answers. But that is actually the great thing about libertarianism and we should use it to our advantage. You don't really have to know much in the way of answers at all. The only answer you need to provide is for the free market, consisting of peaceful individuals, to solve the problem, if there even is a problem.
For example, let's say you get into a discussion about roads. As a libertarian, you suggest that roads would operate better without the government. Maybe you go so far as to say that the government, at all levels, should get out of the road building and operation business entirely. Now someone will challenge you, asking how you would build roads and asking how much the tolls will be.
It is important not to fall into the trap. You don't have to have all of the answers. You don't have to have any of the answers, other than letting the free market work its magic. It would help convince the challenger though if you could provide some examples of possibilities.
Maybe different housing subdivisions would handle their own roads. Maybe businesses would get together and build roads so that customers can access their stores. Maybe some charities would build roads to better their community. Maybe some entrepreneurs would build roads and sell an annual pass to travel on them, or else pay a one-time toll. With modern technology, you could probably pay a toll without stopping your car.
Just because roads would be built and operated outside of the realm of government, it doesn't mean that everyone will necessarily pay for them directly. You don't have to pay to park at most shopping malls. The malls actually provide these parking spots for free, in hopes that you will be more likely to go to the mall and buy things.
It is important to point out to your challenger that you are not a road entrepreneur. You don't really know the best way to build roads or operate them. But even if you are an expert in building roads, you still don't have all of the answers. Only feedback via the marketplace can answer what is right. Only the consumers know what is right. You may build an excellent road that is much better and safer than the average government road. But someone else may come along and use your ideas and improve on them and make an even better road.
Again, you don't have to have all of the answers. It is helpful if you can provide suggestions and possibilities. But it is always important to point out that not having all of the answers is central to your libertarian philosophy. You understand your own limited capabilities. You understand that it is not possible for one person or one small group of people to centrally plan in an effective way. We must rely on prices and profits and losses, as dictated by consumers, to send information as to what works and what doesn't.
Of course, this doesn't just apply to roads. It applies to most issues. That is the great thing about libertarianism. You don't have to know how everything works and you don't have to know the answers. Why do you have to know the answers when you don't want to centrally plan other people's lives? Why do you have to know the answers when there are billions of other people in the world, some of whom do know the answers?