See my Reply #77. There have been attempts to link Basque with many other languages, especially the non-Indo-European ones in the Caucasus like Georgian and Chechen that also seem to be language isolates. The general consensus is still, as far as I'm aware, that no affiliation of Basque to any other language can be shown.
If you're asking about language learning resources, there's a fairly good (although somewhat superficial) introductory text "Colloquial Basque," by Alan King and someone with a Basque name, put out by Routledge which can be purchased in paperback alone or along with tapes.
The language itself is as you'd expect very different structurally from the Indo-European languages, although you might be helped by the fact that in its vocabulary it has borrowed copiously from Spanish.
Here's a series of maps of the world's language famiies:
Map Kernow said: Merritt Ruhlen in his book The Origin of Language, posit a relationship between Basque and languages as disparate as Georgian (Kartvelian), Ket (an obscure, nearly extinct language belonging to a "Yeniseian" language group, because its speakers live along the Yenisei river in Central Siberia), Navajo, and Chinese!
IIRC, Dene-Caucasian includes the Northern (non-Kartvelian) Caucasian languages. Kartvelian may be related to Afro-Asiatic and Nostratic.
By the way, Ruhlen was a student of the late Joseph H. Greenberg, IMHO one of the greatest linguists of the 20th century, if not of all time
Totally agree!
I consider the worldwide etymologies in Ruhlen to be utterly fascinating.