As American nationalists we share several ideas with the libertarians and other constitutionalist conservatives, such as the right to private property, national independence and the support of free-market capitalism.
However there are some elements that differentiate nationalists from conservatives and libertarians, namely that nationalists see government as a means to an end and not as the end itself. Also, nationalists recognize the importance of nation and patriotism more so than libertarians and conservatives.
In the same vein as my post on candidate Gary Johnson, who is more of a demagogue than a true libertarian but whatever, here is a few major criticisms most nationalists agree with and that concern libertarians mostly, but also conservatives to a degree.
Of course immigration is at the top of the list (which should surprise no one) : http://www.nationsiege.com/politics/why-you-cant-be-pro-immigration-and-libertarian