There are some things that I believe in that are not libertarian, for instance, I believe there should be subsidies to get broadband internet service to every rural household in America, just as there was for telephone service and electricity.
I'm against subsidies not because I don't support the end sought (broadband for rural folks), but because subsidies distort markets and are fundamentally anti-competitive. The sentiment is just as wrong as "Every person should own a home" or "Every person should have their college loans paid for" both of which have had disastrous results.
Personally, I, as an urban dweller, see broadband internet as means for rural dweller to not remain backwards and ignorant, and get exposed to other views. Instead, they are led by the nose by two of the richest oligarch brothers in America through shadowy "grass roots" organizations that they fund from their Upper West Side penthouse in Manhattan, and they get them to vote against their own self-interests. They have an extreme hatred for heathcare.gov, even though they've never seen the website and objectively made up their minds. But that's just me.
Without a subsidy to jump start the investment needed in infra-structure, rural dwellers are going to wait a long, long time until the free market solution finally allows them access. Meanwhile, the urban dwellers have the advantage of the information economy, and they don't and society stratifies.
I believe that people and corporations should be made to account for degrading the environment without paying for it (socializing a cost), while making a profit.
Libertarians are pro-property rights, so dumping waste onto others' property or the commons is a big no-no. The argument is about the solution: whether it be central control, or whether it be by privatizing the commons (like has been done with fish stocks) or pigouvian taxes. Libertarians generally prefer the latter because it avoids creating another tragedy of the commons: ensuring the regulatory apparatus is not captured.
I strongly believe in Pigouvian taxes on the dirty energy industry, as it would quickly provide a free market solution to develop the clean energy industry (and get America ahead of the rest of the world in this regard). But I thought the word "tax" was a dirty word with libertarians.