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.
I believe in the right of a group of people to band together and bargain for higher wages and safety standards with a large company or corporation.
Libertarians are all about free association so I don't think any libertarian would disagree with the above.
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.